Buttery Rhubarb Custard Crumble Pie

Rhubarb season is one of those times of year I circle on my calendar. Those tart pink stalks show up at the farmers market, and I know it’s time to start baking. But I never could decide between making a custard pie or a fruit crumble when rhubarb season rolls around.

That’s why this rhubarb custard crumble pie is my go-to recipe now. It’s got the smooth, creamy custard on the bottom and a buttery crumble on top. No more choosing between two good things when you can have both in one pie.

The ginger in here is my secret. It plays so well with the tartness of the rhubarb without taking over. And that crumble topping? It adds just enough sweetness and crunch to balance everything out.

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What Kind of Rhubarb Should I Use?

Fresh rhubarb is always your best bet for this pie, and you’ll find it in grocery stores during spring and early summer when it’s in season. The color of the stalks – whether they’re bright red, pink, or greenish – doesn’t really affect the flavor, so don’t worry too much about finding the reddest stalks. Just make sure the rhubarb feels firm and crisp when you pick it up, and avoid any stalks that look wilted or have brown spots. If fresh rhubarb isn’t available, frozen rhubarb works just fine – just thaw it completely and drain off any excess liquid before chopping it up for your pie.

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Options for Substitutions

This pie is pretty forgiving when it comes to swaps, so here are some options if you need them:

• Unbaked pie shell: Store-bought works great, but if you want to make your own, go for it. You can also use a graham cracker crust for a different twist, though it won’t be quite as traditional.
• Rhubarb: Fresh rhubarb is best for this recipe, but frozen will work in a pinch. Just thaw it completely and drain off any excess liquid before using, or your filling might get watery.
• Eggs: The eggs are key for the custard texture, so I wouldn’t recommend skipping them. If you’re out, you could try using 1/4 cup of unsweetened applesauce plus 1 tablespoon of cornstarch, though the texture will be slightly different.
• Butter in topping: You can use margarine or coconut oil instead, but butter gives the best flavor and texture for that crumbly topping.
• Sugar: If your rhubarb is particularly tart, you might want to add an extra 1/4 cup of sugar to the filling. You can also use brown sugar in the topping for a deeper, caramel-like flavor.

Watch Out for These Mistakes While Baking

The biggest mistake when making rhubarb custard pie is using rhubarb pieces that are too large, which can lead to uneven cooking – cut your rhubarb into small, uniform pieces (about 1/2 inch) so they soften properly and release their juices evenly throughout the custard.

Another common error is skipping the step of mixing the sugar with the rhubarb before adding the eggs, as this helps draw out excess moisture and prevents a watery filling that can make your crust soggy.

To avoid an overbaked crumble topping that turns too dark while the filling is still setting, tent the pie loosely with foil during the last 15-20 minutes of baking if the top is browning too quickly.

Finally, resist the urge to slice into this pie right away – letting it cool completely (at least 2-3 hours) allows the custard to set properly, making for cleaner slices and better texture.

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What to Serve With Rhubarb Custard Crumble Pie?

This pie is pretty rich and sweet on its own, so a simple scoop of vanilla ice cream on the side is always a winner – the cold creaminess balances out the tart rhubarb perfectly. If you’re serving it for a spring brunch or afternoon gathering, pair it with some freshly brewed coffee or hot tea to cut through the sweetness. A dollop of lightly sweetened whipped cream works great too, especially if you want something a bit lighter than ice cream. For a complete dessert spread, consider serving it alongside fresh strawberries or other seasonal berries that complement the rhubarb’s tangy flavor.

Storage Instructions

Store: Keep your rhubarb custard crumble pie covered loosely with foil or plastic wrap in the refrigerator for up to 3 days. The custard filling needs to stay chilled, so don’t leave it out on the counter for more than a couple hours.

Freeze: This pie freezes pretty well for up to 2 months. Wrap it tightly in plastic wrap and then in foil to prevent freezer burn. When you’re ready to eat it, thaw it overnight in the fridge before serving.

Serve: I like to enjoy this pie cold straight from the fridge, but you can also warm individual slices in the microwave for about 20-30 seconds if you prefer it warm. The crumble topping gets a little softer after storing, but it still tastes great!

Estimated Nutrition

Estimated nutrition for the whole recipe (without optional ingredients):

• Calories: 2250-2450
• Protein: 22-28 g
• Fat: 90-105 g
• Carbohydrates: 350-375 g

Ingredients

For the base:

• 1 pie shell

For the filling:

• 1.25 cups sugar
• 3/4 teaspoon salt
• 4 tablespoons flour
• 2 eggs (room temperature, about 70°F)
• 4 cups rhubarb (cut into 1-inch chunks)
• 1/4 teaspoon ground ginger

For the topping:

• 1/2 cup sugar
• 1/2 cup flour
• 1/2 cup butter (I like Kerrygold unsalted butter for this)
• 1/4 teaspoon salt

Step 1: Prepare the Pie Shell and Preheat

• 1 pie shell

Position your oven rack in the lower third of the oven and preheat to 350°F.

This placement helps the bottom crust bake evenly and prevents a soggy base.

While the oven heats, remove your pie shell from the freezer or fridge if it was chilled, allowing it to come to room temperature so it bakes more evenly.

Step 2: Build the Custard Filling Base

• 1.25 cups sugar
• 4 tablespoons flour
• 3/4 teaspoon salt
• 1/4 teaspoon ground ginger
• 2 eggs
• 4 cups rhubarb

In a large mixing bowl, whisk together the sugar, flour, salt, and ground ginger until well combined and no lumps remain.

Add your room-temperature eggs and whisk vigorously until the mixture is smooth and pale, about 1-2 minutes.

This thorough whisking is crucial—it helps the eggs incorporate air and creates a silkier custard texture.

I find that room-temperature eggs blend more smoothly and create a more cohesive filling.

Gently fold in the rhubarb chunks until evenly distributed, being careful not to break the rhubarb pieces too much.

Step 3: Fill the Pie Shell

• rhubarb custard mixture from Step 2
• pie shell from Step 1

Pour the rhubarb custard mixture from Step 2 into the pie shell, spreading it evenly and making sure the rhubarb pieces are distributed throughout.

There’s no need to prebake the shell—the custard and filling work together as the pie bakes.

Step 4: Make the Crumble Topping

• 1/2 cup sugar
• 1/2 cup flour
• 1/4 teaspoon salt
• 1/2 cup butter

In a separate bowl, combine the sugar, flour, and salt for the topping.

Add the cold, cubed butter and use your fingertips or a pastry cutter to work the butter into the dry ingredients until the mixture resembles coarse breadcrumbs with some pea-sized butter pieces remaining.

Don’t overwork this mixture—those small butter pieces are what create the crumbly, textured topping.

I like using Kerrygold butter specifically because its higher fat content creates a richer, more indulgent crumb texture.

Step 5: Assemble and Bake

• crumble topping from Step 4
• filled pie shell from Step 3

Sprinkle the crumble topping evenly over the filled pie, covering all the custard but leaving some gaps so steam can escape and the filling can set properly.

Place the pie in your preheated 350°F oven on the lower rack and bake for 55 minutes to 1 hour and 15 minutes, until the crumble is golden brown and the custard filling is set but still slightly jiggly in the very center when gently shaken—this ensures it won’t be overcooked and dry.

Step 6: Cool and Serve

Remove the pie from the oven and let it cool on a wire rack for at least 30-45 minutes before slicing.

This cooling time allows the custard to fully set and firm up, making clean slices possible.

The pie can be served warm or at room temperature, and it tastes even better the next day when the flavors have melded together.

Buttery Rhubarb Custard Crumble Pie

Delicious Buttery Rhubarb Custard Crumble Pie recipe with step-by-step instructions.

Print Recipe Pin Recipe

Prep Time 25 minutes mins

Cook Time 50 minutes mins

Total Time 1 hour hr 17 minutes mins

Servings 8 slices

Calories 2350 kcal

Ingredients

  

For the base

• 1 pie shell

For the filling

• 1.25 cups sugar
• 3/4 teaspoon salt
• 4 tablespoons flour
• 2 eggs (room temperature, about 70°F)
• 4 cups rhubarb (cut into 1-inch chunks)
• 1/4 teaspoon ground ginger

For the topping

• 1/2 cup sugar
• 1/2 cup flour
• 1/2 cup butter (I like Kerrygold unsalted butter for this)
• 1/4 teaspoon salt

Instructions

 

• Position your oven rack in the lower third of the oven and preheat to 350°F. This placement helps the bottom crust bake evenly and prevents a soggy base. While the oven heats, remove your pie shell from the freezer or fridge if it was chilled, allowing it to come to room temperature so it bakes more evenly.
• In a large mixing bowl, whisk together the sugar, flour, salt, and ground ginger until well combined and no lumps remain. Add your room-temperature eggs and whisk vigorously until the mixture is smooth and pale, about 1-2 minutes. This thorough whisking is crucial—it helps the eggs incorporate air and creates a silkier custard texture. I find that room-temperature eggs blend more smoothly and create a more cohesive filling. Gently fold in the rhubarb chunks until evenly distributed, being careful not to break the rhubarb pieces too much.
• Pour the rhubarb custard mixture from Step 2 into the pie shell, spreading it evenly and making sure the rhubarb pieces are distributed throughout. There's no need to prebake the shell—the custard and filling work together as the pie bakes.
• In a separate bowl, combine the sugar, flour, and salt for the topping. Add the cold, cubed butter and use your fingertips or a pastry cutter to work the butter into the dry ingredients until the mixture resembles coarse breadcrumbs with some pea-sized butter pieces remaining. Don't overwork this mixture—those small butter pieces are what create the crumbly, textured topping. I like using Kerrygold butter specifically because its higher fat content creates a richer, more indulgent crumb texture.
• Sprinkle the crumble topping evenly over the filled pie, covering all the custard but leaving some gaps so steam can escape and the filling can set properly. Place the pie in your preheated 350°F oven on the lower rack and bake for 55 minutes to 1 hour and 15 minutes, until the crumble is golden brown and the custard filling is set but still slightly jiggly in the very center when gently shaken—this ensures it won't be overcooked and dry.
• Remove the pie from the oven and let it cool on a wire rack for at least 30-45 minutes before slicing. This cooling time allows the custard to fully set and firm up, making clean slices possible. The pie can be served warm or at room temperature, and it tastes even better the next day when the flavors have melded together.