In a medium bowl, add coconut flour, sweetener, cinnamon and baking powder. Mix well.
Add melted butter and combine with a spatula.
The mixture will be smooth. Using your fingers, crumble it all up! If it feels too dry, add more butter. You want it to be moist and crumbly, not dry and crumbly.
Sprinkle on top of the berries mixture.
Place cast iron skillet in the oven and bake for 20-25 minutes. The cooking time can be variable to your liking. If the top if getting to brown, simply cover. If you want the berries extra cooked - cook longer covered.
Let sit for 5 minutes to cool down and solidify.
Top with optional whipped cream and serve.