Lightly grease an 8-inch square pan or a 10-inch cast-iron skillet with butter. Rinse the berries and place them in a small bowl. Sprinkle with sugar, cornstarch, and cinnamon. Stir to coat.
In a separate bowl, combine the oats, coconut, flour, brown sugar, and butter. Stir with a fork to create a streusel-like topping.
Scoop half the topping into the prepared pan (see note). Lightly press to cover the bottom of the pan. Pour the berries over the crust, spreading them evenly across the pan. Sprinkle with the remaining crisp topping mixture.
Bake for 25 to 28 minutes, until golden brown. Let cool at least 10 minutes before scooping into bowls.
Notes
To make this recipe gluten-free, use ⅔ cup brown rice flour instead of all-purpose flour.
Frozen blueberries may be substituted for the fresh berries in this recipe. Blackberries and raspberries work well also. If you are using frozen berries, add two tablespoons of water and an additional 2 tablespoons of sugar to the fruit mixture.
If desired, put all of the topping mixture on top of the crisp.