Preheat the oven to 350°F. Line a muffin pan with liners.
To make the topping: Melt the butter for the topping, I like to do this over the stovetop, but you can also microwave it if you prefer.
In a small mixing bowl, add the brown sugar, cane sugar and flour. Add in the melted butter and stir with a spatula until a paste forms. Set aside.
To make the batter: In the bowl of a stand mixer fitted with the paddle attachment, add the butter, dark brown sugar, and cane sugar.
Mix on low until combined and there are no chunks of butter.
Add the bananas and yogurt and mix on low to combine the wet ingredients, you’ll still see chunks of banana and that’s okay.
Add the dry ingredients: flour, baking powder, and sea salt and mix on low until combined.
Add the raspberries and mix on low until combined.
Fill the muffin liners full.
Crumble the topping on top of each muffin.
Bake for 25 to 30 minutes, until a toothpick inserted in the center comes out clean.
Store in an airtight container for up to 5 days.