Spinach Quiche - Recipook

Ingredients

• 1/2 cup butter
• 1 small onion, chopped
• 3 cloves garlic, chopped
• 1 (10 ounce) package frozen chopped spinach, thawed and drained
• 1 (4.5 ounce) can mushrooms, drained
• 1 (6 ounce) package herb and garlic feta, crumbled
• 1 (8 ounce) package shredded Cheddar cheese, divided
• salt and pepper to taste
• 1 deep-dish pie shell
• 4 eggs
• 1 cup milk