Heat oven to 375F. Grease a 9"x13" baking tray or a 6” cast iron skillet.
In a mixing bowl, combine 907 g blueberries, 20 g sugar, 1 Tbsp cornstarch, 1/2 tsp fresh ground black pepper, and pinch of salt. Toss to combine until blueberries are evenly coated. Set aside.
In a separate mixing bowl, combine 200 g all purpose flour, 80 g oats, 120 g granulated sugar, 170 g unsalted butter, and pinch of salt. Use your hands to combine, pressing the mixture through your fingertips until it forms pea-sized pieces.
Add the blueberry mixture to the bottom of your pan in an even layer. Loosely spread the crumble in an even layer on top of the blueberries.
Bake at 375F for 25-30 minutes, until the crumble is golden brown on top.
Spoon the warm crumble into bowls and serve with ice cream.