- 2 cups chopped sweet onion
- 2 cups mayonnaise
- 2 cups shredded Cheddar cheese
- Preheat oven to 350 degrees F (175 degrees C).
- Stir sweet onion, mayonnaise, and Cheddar cheese together in an casserole dish.
- Bake in preheated oven until golden and bubbly, 15 to 20 minutes.