Squash-and-Onion Gratin

Directions

1. 1
   Combine zucchini and onions in a large stockpot.
2. 2
   Cover with water, and boil until the vegetables are tender, about 30 minutes.
3. 3
   Drain in a colander, pushing firmly to extract all the liquid.
4. 4
   Combine the Gruyere, ricotta, garlic, salt and pepper.
5. 5
   Add the vegetables, mix well and adjust the seasonings.
6. 6
   Butter a 3-quart casserole and fill with the squash mixture.
7. 7
   Cover with plastic wrap and refrigerate until ready to cook.
8. 8
   Preheat oven to 400 degrees.
9. 9
   Uncover the casserole and bake on middle shelf until golden brown and bubbly, about 30 minutes.