Spinach Quiche Appetizer Squares

Spinach Quiche Appetizer Squares
1 C all purpose flour
1 tsp baking powder
1 tsp salt
2 large eggs, lightly beaten
6 tbsp butter, melted
1 C milk
1/2 medium onion, minced (I omit this and just add onion powder)
4 C (16 oz) finely shredded sharp cheddar cheese (I have also used a blended cheese, like Monterrey jack & colby)
1 (10 oz) packaged frozen chopped spinach, thawed and well drained

Combine flour, baking powder & salt in a large bowl: add eggs, butter & milk, stirring well. Stir in onion, cheese & spinach. Pour spinach mixture into a lightly greased 9x13x2 inch pan. Bake at 350 degrees for 40 - 45 minutes (in my oven, it is done in about 35 minutes - so check it after about 30 minutes) or until golden. Let stand at room temperature 3 - 5 minutes before cutting into squares. Makes about 24to 36 squares.