Heat the oven to 350°F. Peel the squash, leaving the skin in the crevices (it's tender enough to eat). Trim the ends. Cut the squash in half lengthwise and scoop out the seeds. Slice the halves crosswise 1/2 inch thick.
Heat 1 Tbs. of the oil in a 10-inch skillet over medium-high heat. Add half of the squash in a single layer and cook without moving until the slices begin to brown, about 2 minutes. Flip and cook until the second side begins to brown, 1 to 2 minutes. Transfer to a 9x13-inch baking dish. Repeat with the remaining squash. Arrange the squash in a single layer in the dish. Sprinkle with 2 Tbs. of the sherry, 1/2 tsp. salt, and a few grinds of pepper.
Heat the remaining 1 Tbs. olive oil and the butter in the skillet over medium heat. Add the shallots and a pinch of salt and cook, stirring frequently, until the shallots turn deep golden brown on the edges, 3 to 5 minutes. Take the pan off the heat and immediately add the sage and the remaining 2 Tbs. sherry, scraping up the browned bits on the bottom of pan. Scatter the shallots over the squash.
Cover the pan with foil and bake until the squash is tender when pierced with a fork, 25 to 30 minutes. Season to taste with salt and pepper.
Make Ahead Tips
You can assemble this dish up to 2 hours before baking.
nutrition information (per serving):
10, Fat Calories
90, Saturated Fat
3, Monounsaturated Fat
19, Polyunsaturated Fat
Photo: Scott Phillips