Squash Casserole - Miz En Place

Ingredients

• 1 tbsp vegetable oil
• 1 tbsp butter
• 2 pounds summer squashes, thinly sliced
• 1 large Vidalia onion, thinly sliced
• 1/2 cup grated parmesan cheese
• 1 cup shredded sharp cheddar cheese
• 1/2 cup sour cream
• Salt and pepper, to taste
• 1 sleeve crushed butter crackers