Preheat the oven to 350°F (175°C). Grease a muffin tin or line it with paper liners.
In a mixing bowl, combine the chopped spinach, grated cheese, and both types of flour.
In another bowl, whisk together the milk, olive oil, and eggs until well blended.
Add the wet ingredients to the dry ingredients and stir until just combined. Be careful not to overmix.
In a small bowl, mix the baking powder, salt, black pepper, garlic powder, and onion powder. Fold this mixture into the muffin batter until evenly distributed.
Divide the batter evenly among the 12 muffin cups.
Bake in the preheated oven for about 20 minutes, or until the muffins are golden brown and a toothpick inserted into the center comes out clean.
Allow the muffins to cool in the pan for 5 minutes before transferring them to a wire rack to cool completely.