Preheat your oven to 375°F (190°C). Line your muffin tin with parchment liners or grease them to prevent sticking.
In a large mixing bowl, whisk together the white whole-wheat flour, baking powder, baking soda, paprika, sea salt, and black pepper until well combined.
In another bowl, mix the milk, melted coconut oil (or butter), beaten egg, and lemon zest. Stir until the mixture is smooth and uniform.
Pour the wet ingredients into the bowl with the dry ingredients. Gently fold the mixture using a rubber spatula until just combined. Be careful not to overmix; it's okay if there are a few lumps!
Now, gently fold in the chopped spinach, crumbled feta cheese, and finely chopped chives. This adds a burst of flavor and nutrients to your muffins.
Scoop the batter into the prepared muffin tin, filling each cup about three-quarters full.
Place the muffin tin in the preheated oven and bake for 18-20 minutes, or until a toothpick inserted into the center comes out clean.
Once baked, let the muffins cool in the pan for about 5 minutes before transferring them to a wire rack to cool completely. Enjoy them warm or store them for later!