2tablespoonslemon juice(about half a medium lemon)
Preheat oven to 375°F with a rack placed in the center of the oven.
Whisk together the flour, sugar, baking powder, and salt in a bowl. Cut the butter into the flour until it looks like coarse crumbs using a pastry cutter, two forks, or your fingers. Mix in the vanilla, egg, and vinegar and stir together until the dough comes together and the flour is fully incorporated.
Place half of the dough into a 2-quart baking dish or deep-dish pie pan. Scatter it evenly to cover the bottom of the pan and press it down to make an even layer.
Combine the blackberries, sugar and cornstarch in a bowl, and toss to mix. Stir in the lemon juice and lemon zest. Place the blackberry mixture in the baking dish and spread evenly.
Spread the remaining topping evenly over the fruit, using your fingers to clump some of the dough. Bake until the top is light brown and crisp, about 40-45 minutes.
Remove the crumble from the oven and cool on a wire rack for about 30 minutes. Serve warm with ice cream.
Adapted from Ultimate Berry Crumble, AllRecipes.
You can easily assemble the topping or the whole crisp in advance. Cover tightly and place in the freezer until you are ready to bake. That makes one less thing to worry about when you’re entertaining!
Make it vegan:
Fruit crumble is easy to make vegan. Simply substitute the butter for your favorite vegan butter (I especially love using Miyoko's vegan butter, which is available at most major grocery stores). Serve with non-dairy ice cream.
Can I use frozen blackberries?
Yes, absolutely. This can come in handy when blackberries are not in season.