01 - Preheat the oven to 375°F and prepare a 12-cup muffin tin with paper liners or by greasing it thoroughly.
02 - In a large bowl, whisk together all-purpose flour, baking powder, baking soda, salt, and black pepper until well mixed.
03 - In a separate bowl, whisk eggs, whole milk, olive oil, and Greek yogurt until fully blended and smooth.
04 - Pour the wet ingredients into the dry ingredients and stir gently just until combined, avoiding overmixing to maintain muffin fluffiness.
05 - Fold the cheddar, feta, red bell pepper, spinach, chives, and parsley into the batter evenly.
06 - Distribute the batter evenly into the prepared muffin cups, filling each about three-quarters full.
07 - Bake for 22 to 25 minutes, or until a toothpick inserted in the center comes out clean.
08 - Allow the muffins to cool in the tin for 5 minutes before transferring them to a wire rack to cool completely.