Spinach Gratin Casserole – Excavating Linda

Ingredients

• 3 pkg frozen spinach, thawed
• 1 pkg frozen mixed vegetables
• 1 onion, chopped
• 1 1/2 Tbsp butter
• 1 1/2 Tbsp olive oil
• 3 cloves garlic, chopped
• 1 cup sliced mushrooms
• 1 cup milk (or cream)
• 2 large eggs
• 1/2 cup blue cheese crumbles
• 1/2 cup shredded old cheddar
• 1/2 cup shredded swiss or asiago
• 1/4 cup shredded parmesan