Preheat your oven to 375°F (190°C). Lightly spray an 8 or 9-inch baking dish with nonstick cooking spray and set it aside. This ensures the crisp won't stick to the pan and makes serving easier.

In a medium bowl, whisk together the all-purpose flour, brown sugar, baking powder, salt, and ground cinnamon. Add the melted butter and stir with a fork until the mixture forms coarse, crumbly clumps. This mixture will become the delicious crisp topping.

In a large bowl, combine the peeled, cored, and chopped Granny Smith apples with the granulated sugar, lemon juice, cornstarch (or all-purpose flour if substituting), ground cinnamon, and salt. Toss everything together until the apples are evenly coated and the mixture looks glossy and well mixed. I like to use Granny Smith apples for the tartness—they balance out the sweet topping perfectly.

Transfer the apple filling from Step 3 into the prepared baking dish and spread it into an even layer. Sprinkle the crumble topping from Step 2 evenly over the apples, making sure to cover most of the fruit for a crunchy finish.

Bake the assembled apple crisp in the preheated oven for 35 to 45 minutes, or until the filling is bubbling and the topping is golden brown. Let the crisp cool for at least 15 minutes before serving. For an extra special touch, I love scooping a little vanilla ice cream on top when serving—it melts just right over the warm crisp!