Berry Crumb Bars

Preheat oven to 375° F. Line a 9x13-inch baking dish with parchment paper and set aside.
In a medium bowl, combine the flour, 1 cup of sugar, baking powder, salt, and lemon zest. With a pastry cutter, cut in the butter and the egg to make a crumbly dough with bits of butter throughout. Pat half of the crumb mixture into the prepared dish.
3 cups (360 grams) all-purpose flour, 1 cup (199.5 grams) granulated sugar, 1 teaspoon baking powder, ¼ teaspoon salt, 1 tablespoon fresh lemon zest, 1 cup (227 grams) cold unsalted butter, 1 large egg
In another bowl, combine remaining sugar, lemon juice, and cornstarch. Gently fold in the berries and pour evenly over the crust. Take the other half of the crumb mixture and sprinkle on top of the berries.
0.5 cup (100.5 grams) granulated sugar, 2 tablespoons fresh lemon juice, 1 tablespoon cornstarch, 5 cups (775 grams) fresh berries
Bake for 45-50 minutes until the top has slightly browned.
Let bars cool completely to room temperature (or chill in the fridge for even sturdier slices), then use the parchment paper to lift the bars out of the pan and transfer to a cutting board.
Store crumb bars at room temperature for up to 2 days, or in the fridge for up to 7 days (my preferred storage method).