It helps tremendously to line the baking pan with parchment so you can lift the entire lot out in one fell swoop. But buttering and flouring the pan works, too. However you do it, be sure to let the crumble cool to room temperature before cutting it into squares or they may fall apart.
While considered a dessert, crumble makes a quick and easy breakfast with just the right amount of a sugar rush to start your day. They’re great for a mid-afternoon snack, too. Leftovers can be frozen in a well-sealed airtight container for about two months.
STRAWBERRY-BLUEBERRY CRUMBLE BARS
For crust and topping
1 cup granulated sugar
1 teaspoon baking powder
3 cups all-purpose flour
Pinch of salt
Zest of 1 lemon
1 cup cold unsalted butter, cut into cubes
1 large egg
1/2 teaspoon pure vanilla or almond extract
For berry filling
2 1/2 cups blueberries
2 cups chopped strawberries
1/2 cup granulated sugar
4 teaspoons cornstarch
Juice and zest of 1 small lemon
1/2 cup toasted slivered almonds
Preheat oven to 375 degrees. Line a 9- by 13-inch baking pan with foil or parchment paper, or prepare it with butter and a dusting of flour.
Prepare crust/topping: On low speed, combine granulated sugar, baking powder, flour and salt in the bowl of a stand mixer outfitted with a paddle. Add lemon zest, butter chunks, egg and vanilla or almond extract. Beat on low speed until the butter is evenly distributed in pea-sized pieces and the mixture is crumbly. (It should come together when pressed between your fingers.)
Dump about ⅔ of the mixture into the bottom of the prepared pan. Use your fingers or the bottom of a glass to evenly press the dough into the pan, making sure to fill the corners. Set aside while you prepare the filling.
In a large bowl, gently stir together berries, cornstarch, sugar and lemon juice and zest until well incorporated. Spread the filling over the crust, then sprinkle the remaining dough mixture over the top of the berries. Sprinkle toasted almonds evenly on top;
Bake for 45-50 minutes, until the top is light golden brown and fruit looks jammy. Transfer pan to a rack to cool completely before cutting into squares.
Makes 16-20 squares.