Preheat oven to 350°. Toss together washed, stemmed blueberries and granulated sugar in a bowl, then transfer to a medium baking dish.
Combine flour, brown sugar, and a pinch of salt in another bowl. Using two knives, work cold butter, cut into pieces, into flour mixture until it resembles coarse meal. Sprinkle mixture evenly over blueberries.
Bake until berries are bubbling and topping is golden, about 50 minutes. Allow to cool for 15 minutes. Serve warm or at room temperature with heavy cream spooned over top.