Preheat the oven to 350°F/180°C. Lightly spray the muffin tin with coconut oil.
In a large bowl, stir together the following ingredients: yogurt, peanut butter, eggs, oat flour, brown sugar, coconut oil, baking soda, and powder. Whisk until well combined.
Fill the muffins cups about 3/4. Insert a piece of chocolate into the center of each, pressing down slightly.
Add one more Tbsp of batter to cover it completely, then sprinkle with chocolate chips.
Bake for 18-20 minutes or until a toothpick inserted in the center comes out clean. (if the muffins are small, then cook them for about 15 minutes)