Blueberry Buckle

255 grams cake flour
1 teaspoon baking powder
½ teaspoon kosher salt
½ teaspoon ground ginger
4 tablespoons (½ stick) unsalted butter, left at room temperature for 30 minutes
150 grams sugar
1 large egg
½ cup whole milk
425 grams (15 ounces) fresh blueberries

Combine the sugar, flour and nutmeg in a small bowl then work in the butter, using a fork to combine. Keep "forking" until the mixture has a crumb-like texture. Set aside. (Note: If you have a pastry cutter, now's the time to use it.)

Heat the oven to 375° F. Spray a 9-inch square GLASS baking dish with nonstick cooking spray and set aside.
Whisk the flour, baking powder, salt and ginger together in a medium bowl and set aside.
Beat together the butter and sugar in a stand mixer fitted with the paddle attachment on medium speed until light and fluffy, approximately 1 minute. Reduce the speed a bit and thoroughly incorporate the egg. Reduce the speed to low (or "stir" on a Kitchenaid) and add one-third of the flour mixture. Once incorporated, add one-third of the milk then repeat alternating until all ingredients are combined.
Gently stir in the blueberries and pour the mixture into the prepared baking dish and sprinkle on the topping mixture.
Bake on the middle rack of the oven for 45 minutes, or until golden. Cool for 30 minutes before serving.