Preheat the oven to 375°F. Grease an 8 x 11 baking dish (or similar size).
In a large bowl, combine the strawberries and blueberries. Sprinkle with dry cornstarch and 1 tablespoon of brown sugar. Stir to coat berries.
Into the bowl of a food processor (or medium bowl if mixing by hand), add the flour, sugar and remaining 1/2 cup brown sugar, baking powder and salt. Pulse a few times to combine. Add the egg, vanilla and almond extract pulse to combine. Add butter to processor and pulse until mixture is the texture and size of crumbs.
Sprinkle the crumb mixture evenly over the berries.
Bake on center rack of oven for 45 - 50 minutes, or until top is golden and berries are bubbling. Remove from the oven and cool slightly before serving.