01 - Preheat the oven to 375°F. Line a 12-cup muffin tin with paper liners or grease thoroughly.
02 - In a large bowl, whisk together all-purpose flour, baking powder, baking soda, salt, and black pepper until evenly distributed.
03 - In a separate bowl, whisk eggs, whole milk, olive oil, and Greek yogurt until the mixture is smooth and uniform.
04 - Pour the wet ingredients into the dry ingredients and gently stir until just combined, avoiding overmixing to maintain fluffiness.
05 - Carefully fold in the grated cheddar, crumbled feta, diced red bell pepper, chopped spinach, fresh chives, and parsley evenly through the batter.
06 - Spoon the batter evenly into the prepared muffin cups, filling each about three-quarters full to allow for rising.
07 - Bake for 22 to 25 minutes or until a toothpick inserted into the center comes out clean, indicating they are fully cooked.
08 - Allow muffins to cool in the tin for 5 minutes, then transfer to a wire rack to cool completely before serving.