Set the rack in the middle of the oven and preheat the oven to 375 degrees Fahrenheit.
In a large bowl, gently mix the 2 cups quartered strawberries, 1 cup blueberries, 1 cup raspberries, ⅓ cup granulated sugar, and 3 tablespoons all-purpose flour.
Evenly divide the berry filling into 4 8-ounce-sized ramekins, about 1 cup per dish.
Crisp Topping
Mix together ¼ cup all-purpose flour, ¼ cup old-fashioned rolled oats, 2 tablespoons brown sugar, ¼ teaspoon cinnamon, ⅛ teaspoon kosher salt, ⅛ teaspoon nutmeg, and ⅛ teaspoon ground ginger in a small bowl.
Cut the 3 tablespoons unsalted butter into small ¼-inch pieces and add to the flour mixture. Use your fingers to mix the butter into the dry ingredients, pressing together to create pea-sized pieces.
Evenly sprinkle the topping over the berry mixture in the dishes, about ¼ cup per ramekin.
Place the ramekins on top of a foil-lined baking sheet and bake for 25-30 minutes until the crisp topping is golden brown.