01 -
Position an oven rack in the center of the oven and preheat to 175 degrees Celsius (350 degrees Fahrenheit). Line a 12-cup muffin pan with paper liners.
02 -
Whisk together the flour, protein powder, baking powder, cinnamon, baking soda, and salt in a medium bowl until well combined.
03 -
In a large bowl, whisk the brown sugar, Greek yogurt, coconut oil, vanilla extract, and eggs. Stir in the mashed banana until fully incorporated.
04 -
Gradually fold the dry ingredients into the wet ingredients, mixing until just combined.
05 -
Fill each paper liner halfway with batter. Add 2 teaspoons of peanut butter to the center of each, then top evenly with the remaining batter, leaving the liners nearly full.
06 -
Bake in the preheated oven until the muffins are golden brown and a toothpick inserted in the center comes out clean, about 30–35 minutes. Let cool for 5 minutes in the pan, then transfer to a wire rack to cool completely.
07 -
Store muffins in an airtight container at room temperature for up to 4 days.