Butternut Squash With Spinach Au Gratin

Yesterday I shopped at Trader Joe's.  The sampling was two of my favorite vegetables, butternut squash and spinach au gratin.  The offering was paired with a pork roast.  I can usually find a recipe and tweak it to what I think resembles the flavor I want when making the dish.   This is my offering.  
Serves 6

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Butternut Squash and 
Creamed Spinach Au Gratin

1 1/2 pounds fresh spinach , stems discarded or 
   16 oz. frozen spinach, thawed  

2 1/2 to 3 Tablespoons butter, plus additional for   
   greasing the baking dish. 
3/8 cup finely chopped onion

1 teaspoon garlic, minced

3/4 teaspoon salt

3/8 teaspoon freshly ground pepper

Rounded 1/8 teaspoon freshly grated nutmeg

1/2 cup heavy cream

2 pounds butternut squash, peeled, seeded and 
    quartered.

Parmesan cheese for topping

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If using fresh spinach, bring 1 inch of water to a boil in a 6 to 8 quart pot over high heat.  Add spinach a few handfuls at a time with tongs, until wilted, 3 to 5 minutes.  Drain in a colander and rinse under cool water.

Thoroughly squeeze cooked or frozen spinach in small handfuls to remove excess moisture, then coarsely chop and transfer to a bowl.

Melt 1 1/2 tablespoons butter in an 8 inch heavy skillet over moderately low heat, then cook onion until softened 3 to 5 minutes, add garlic and cook 1 minute more.  Add mixture to spinach along with salt and pepper, nutmeg, and cream; stir to combine. 

Put oven rack in upper third of oven and preheat oven to 400 F.  Butter a shallow baking dish.  I used a 7 X 10 baking dish.

Cut squash to separate bulb section from solid neck section, then cut pieces lengthwise into lengthwise pieces into 1/8 inch thick slices or slicer.

Layer squash and spinach mixture in baking dish, using squash as bottom layer and ending as top layer, layering with three layers of squash and two layers of spinach.  Dot with  remaining 1 1/2 tablespoons butter and sprinkle with cheese.  Cover with parchment or waxed paper.  Bake until squash is tender and bubbly 30 to 35 minutes depending on the thickness of the squash slice.  Check to make sure squash is fork tender.  Remove paper and bake until au gratin is browned in spots, 10 to 15 additional minutes or broil 3 inches from heat, 2 to 3 minutes.