Here's a good recipe:
Butternut Squash Gratin (from chow.com)
2 lbs. butternut squash, peeled and seeded
1 1/2 cups heavy cream
1/2 cup half and half
2 bay leaves
3 sprigs fresh thyme (or 1/8 tsp. ground thyme)
1/8 tsp. ground mace
1 3/4 tsp. kosher salt
1/2 tsp. ground black pepper
3 Tbsp. butter
1 medium-sized yellow onion
1 tsp. minced garlic
1/4 cup finely grated Parmesan cheese
-Slice squash in quarter-inch slices. In a heavy-bottomed sauce pan, combine the squash, cream, half and half, bay leaves, thyme, mace, 1 tsp. of the salt and 1/4 tsp. of the pepper. Simmer over moderate heat, stirring lightly to distribute the liquid, until squash is tender and has absorbed most of the liquid, approximately 30 minutes.
-Meanwhile, slice the onions about a 1/4-inch thick (or a little less thick if you prefer). Melt half the butter in a large skillet and saute the onions until they turn deep golden brown. Add the qarlic and cook for one minute, stirring frequently. Season with the remaining salt and pepper.
-In an oiled, shallow, medium-sized baking dish, layer the squash mixture and onions. Sprinkle with parmesan cheese and dot with the remaining butter.
-Preheat oven to 425 degrees F and bake for 15 minutes or until lightly browned and bubbly.
Serves 6-8 people.
Note: If multiplying the recipe 4x or more, use less liquid or it will get too soupy. Multiplying 5x uses 1-2 cups less liquid.
This can be made in advance and reheated or kept uncooked in the fridge and brought to room temp. before baking. It also freezes well after being baked. Leftovers make a great soup, pureed and thinned with chicken or vegetable stock.