Preheat the oven to 375 degrees and line a muffin pan with cupcake liners or spray the tin with cooking spray.
Measure 2 cups all-purpose flour, spooned and leveled, ⅔ cup light brown sugar, firmly packed, ½ cup cocoa powder, 1 Tablespoon baking powder, ½ teaspoon sea salt into a large bowl and use a whisk to combine. Stir in ¾ cup chocolate chips.
In a medium bowl, mash 1 ½ cups very ripe banana, mashed, 3 or 4 bananas depending on size, then whisk in 1 large egg, ¾ cup plain whole milk yogurt, room temperature, ½ cup coconut oil and 1 teaspoon vanilla extractuntil well combined.
Add the combined wet ingredients to the bowl of dry ingredients and fold in until just combined. The batter will be thick.
Divide the batter evenly into 12 prepared muffin cups and sprinkle with the remaining ¼ cup of chocolate chips as desired. The cups will be full and mounded.
Bake for approximately 20 to 25 minutes, until a toothpick inserted into the center comes out clean.
Allow muffins to cool in the tin for 5 to 10 minutes, then remove them from the tin and place them on a cooling rack. Enjoy warm or cooled to room temperature.