Preheat the oven to 375°F (190°C) and grease or line a muffin tin with paper liners.
In a large mixing bowl, combine the all-purpose flour, baking powder, garlic powder, onion powder, salt, and black pepper. Mix well.
In another bowl, whisk together the milk, vegetable oil, and eggs until thoroughly combined.
Add the chopped spinach, shredded cheese, and grated Parmesan to the wet ingredients, mixing until evenly distributed.
Pour the wet ingredients into the dry ingredients, stirring gently until just combined. Be careful not to overmix; it’s okay if there are a few lumps.
Divide the batter evenly among the 12 muffin cups, filling each about two-thirds full.
Bake in the preheated oven for 20 minutes, or until the muffins are golden-brown and a toothpick inserted in the center comes out clean.
Remove from the oven and let the muffins cool in the tin for 5 minutes before transferring them to a wire rack to cool completely.
Feel free to add extras such as cooked bacon, finely chopped bell peppers, or herbs for added flavor.
Serve with a dollop of yogurt or a spread of cream cheese for extra taste. Enjoy!