Simple Mozzarella Spinach Bars are a tasty appetizer or snack that sneaks in a powerful amount of spinach. Add in your favorite veggies to customize.
Preheat oven to 375°F.
In a saucepan, saute the onions, garlic, and spinach. Cover the pan and let spinach wilt, about 3 minutes.
In a large bowl, mix together flour, salt, baking powder, eggs, milk, cheese, and butter.
Pour the batter into a baking dish.
Bake for 30 to 35 minutes, or until a toothpick inserted in the center comes out clean.