Preheat the oven to 425°F. Line a standard 12-cup muffin tin with paper liners and lightly spray the liners with nonstick baking spray. Set aside.

Place a large mixing bowl on the counter. Add the mashed bananas and use a fork to mash until mostly smooth, leaving a few small chunks for texture.

Add the melted butter, granulated sugar, egg, and vanilla extract to the bananas. Using a whisk, mix until the batter is smooth and fully combined.

In a separate medium bowl, add the flour, cocoa powder, baking soda, baking powder, and kosher salt. Whisk until evenly combined and no cocoa lumps remain.

Add the dry ingredients to the banana mixture. Using a rubber spatula, gently fold the batter together just until no dry streaks remain. Do not overmix.

Fold in the chocolate chips and freeze-dried strawberries until evenly distributed.

Divide the batter evenly among the prepared muffin cups, filling each about three-quarters full.

Press a few additional chocolate chips and diced fresh strawberries gently into the top of each muffin.

Place the muffin tin in the oven and bake at 425°F for 5 minutes. Without opening the oven door, reduce the oven temperature to 350°F and continue baking for 10 to 12 minutes, until the tops are set and spring back lightly when touched. A toothpick inserted into the center should come out with moist crumbs, not wet batter.

Remove the pan from the oven and let the muffins cool in the tin for 5 minutes. Transfer the muffins to a wire rack to cool completely.