Recipe: Roasted Butternut Squash and Onion Gratin (Κολοκύθα και Κρεμμύδια στο Φούρνο)

It's been snowing off and on for three days. Today the wind started up. I went outside to retrieve the garbage can lid and came back chilled to the bone.

For dinner, I wanted something solid and warming, so decided to roast butternut squash and turn it into a gratin. To balance the squash's sweetness, I added caramelized onions and nutty graviera cheese.

The result was exactly what I wanted. By the time dinner was over, I was warm and cozy and once again enjoying our snowy vistas.

Roasted Butternut Squash and Onion Gratin (Κολοκύθα και Κρεμμύδια στο Φούρνο)
Serves 4 - 6 as a main course or 8 - 12 as a side dish
The gratin may be baked in either a 9” square pan or a 9” x 13” pan, depending on whether you want a thicker gratin (use the square pan) or more area of cheese crust (use the rectangular pan). I cut up and roast the squash in olive oil before layering it with onions. I do this because caramelizing the squash significantly improves the gratin’s flavor. If you want to avoid olive oil, cut the squash in half, roast halves on parchment paper - cut-side down - at 375°F until tender, scoop out the flesh, and cut into 3/4” dice.

2 1/2 pound butternut squash (2 pounds cleaned; 6 cups cut in 3/4” dice)
4 cups diced onions (1/2” dice) (1 1/2 pounds)
4 Tbsp. olive oil, divided
Salt
Freshly ground black pepper
4 tsp. minced garlic
1 tsp. Aleppo pepper or 1/2 tsp. crushed red pepper (optional)
4 tsp. minced fresh rosemary
4 tsp. minced fresh thyme
1 - 2 cups (4 ounces) grated graviera, comte, or gruyere cheese (1 cup for 9” pan, 2 cups for 9” x 13” pan)
1 cup half and half

Preheat oven to 450°F.

Roasting the Squash: Remove the skin of the squash with a knife or vegetable peeler, cut in half and remove the seeds, and cut into 3/4” dice. Put the squash on a rimmed baking sheet and toss it with salt, freshly ground black pepper, and 2 tbsp. olive oil. Bake for 40 – 45 minutes or until the squash is browned on at least one side. Remove from the oven. (The recipe may be made ahead to this point.) Turn the oven heat down to 375°F.

Cooking the Onions: While the squash is cooking, sauté the onion, lightly seasoned with salt and freshly ground black pepper, in the remaining 2 Tbsp. olive oil until it starts to brown. Add the garlic and Aleppo pepper and cook for 1 minute. Turn off the heat, and stir in the rosemary and thyme. (The recipe may be made ahead to this point.)

Layering the Gratin: In an oiled baking pan, spread out half the onions. Top with a layer of roasted squash, then a layer of the remaining onions, then a layer of the cheese. Pour the half and half evenly over the cheese. Bake at 375°F for 30 – 40 minutes or until the cheese has formed a nice brown crust. Serve immediately.