Preheat your oven to 350°F. While the oven heats, generously butter a 9x13-inch baking dish, making sure to coat the bottom and sides evenly—this prevents sticking and helps develop a golden crust. Spread the cubed French bread evenly across the bottom of the dish, then distribute the diced ham and shredded Cheddar cheese evenly over the bread. This layering approach ensures every bite has a balanced mix of bread, ham, and cheese.

In a large bowl, crack the room-temperature eggs and whisk them together until the whites and yolks are fully combined. Add the milk, Dijon mustard, minced fresh thyme, garlic powder, salt, and black pepper. Whisk vigorously for about 1-2 minutes until the mixture is smooth and well-blended. I find the Dijon mustard adds a subtle savory depth that really elevates the flavor without making it taste like mustard—trust me on this one. The room-temperature eggs whisk more easily and incorporate air for a lighter, fluffier final texture.

Pour the custard mixture from Step 2 slowly and evenly over the layered bread, ham, and cheese in the prepared baking dish from Step 1. Use a fork or spatula to gently press down the bread cubes so they absorb the egg mixture, but don't compact them too much—you want a light, airy texture. Let the dish sit for 2-3 minutes to allow the bread to soak up some of the custard, then place it in the preheated 350°F oven. Bake for 45 to 55 minutes, until the top is golden brown and a knife inserted in the center comes out clean or with just a few moist crumbs.

Remove the bake from the oven and let it rest for 5 minutes before serving. This resting period allows the custard to set slightly and makes it easier to cut clean portions. Garnish with fresh thyme leaves if desired for a bright, herbaceous finish and a pop of color. Serve warm, cut into squares.