01 - Preheat the oven to 350°F. Line a muffin tin with paper liners or lightly grease each cup.
02 - In a large mixing bowl, whisk together whole wheat flour, protein powder, unsweetened cocoa powder, ground cinnamon, baking powder, baking soda, and salt until well blended.
03 - In a separate bowl, beat the eggs. Add unsweetened applesauce, Greek yogurt, brewed espresso or strong coffee, honey or maple syrup, melted coconut oil or neutral oil, and vanilla extract. Mix until smooth and uniform.
04 - Pour the wet mixture into the bowl with dry ingredients. Stir gently until just incorporated, taking care not to overmix.
05 - If using, gently fold mini chocolate chips and chopped nuts into the batter.
06 - Divide batter evenly among the muffin cups, filling each about three-quarters full.
07 - Place the pan in the oven and bake for 16 to 18 minutes, or until a toothpick inserted in the center comes out clean or with a few moist crumbs.
08 - Let muffins cool in the tin for 5 minutes. Then transfer to a wire rack to cool completely before serving.