Heat oven to 400°F
Spray bottoms of 3 mini loaf pans (5-1/2x3 inches).
In large bowl, whisk together flour, cheese, sugar, baking powder, basil, onion powder, salt and pepper.
In medium-size bowl, whisk egg, milk and oil until blended; stir in spinach.
Make a well in the flour mixture; pour in egg mixture. Fold or stir gently until dry ingredients are just moistened.
Spoon 1 cup batter into each mini loaf pan. If desired, sprinkle 1 teaspoon grated Parmesan over each loaf.
Bake for 25 to 30 minutes or until toothpick inserted in center comes out clean.
Remove pans to wire rack and cool for 5 minutes. Remove bread from pans; cool on rack.
NOTE: For muffins, coat bottoms of muffin pans with cooking spray or line with muffin-cup liners. For 12 standard muffins, spoon 1/4 cup batter into each cup. Bake for 20 minutes.
For 36 mini muffins, prepare 3 mini muffin pans. Spoon 1 slighty rounded tablespoon batter into each cup. Bake for 15 minutes.