Cheesy Baked Pasta with Spinach and Mushrooms

This is like a gourmet version of mac 'n' cheese. Even though it has lots of veggies, my two girls liked it. I guess that isn't saying a lot since they both tend to like vegetables, depending on the kind. For some reason they like mushrooms, even though that was the one food, as I can remember, that I didn't like as a kid. They must get it from their dad :)

Cheesy Baked Pasta with Spinach and Mushrooms Recipe, serves 4
10 oz mini penne or corkscrew pasta
2 Tbs butter or rendered bacon fat plus more if needed
1 large shallot (or half an onion), chopped finely
1 package sliced mushooms
1 Tbs tapioca flour or  2 Tbs all-purpose flour
2 cups milk
½ tsp sea salt
½ tsp garlic powder (not garlic salt)
several turns of the pepper mill
a good grating of nutmeg (if you're using ground, about ¼ tsp)
½ cup shredded mozzarella
¾ cup grated Parmesan or Romano cheese, divided
2 cups chopped spinach (or other hearty green)

Cook pasta according to package directions, but drain a minute or two early so it's nice and al denté. Reserve about a cup of pasta water in case your sauce needs thinning.

Preheat oven to 400ºF and position rack in lower third.

Meanwhile, melt butter or lard in Dutch oven. When hot, add shallot and cook, stirring, until tender. Add mushrooms and cook, stirring, until browned and tender. Add tapioca flour and stir, cooking for one minute. Whisk in milk and add salt, garlic powder, pepper and nutmeg. Bring up to a boil, stirring constantly, and immediately reduce heat to low simmer and cook until sauce is thickened. Add mozzarella and ½ cup of the Parmesan. Stir to melt and incorporate and remove from heat. Stir in spinach just to wilt. Add pasta and stir to combine everything. Top with remaining Parmesan and place in oven for about 10 mins, until everything is bubbly. Turn oven to broil and broil about 3 minutes, until cheese is nicely browned. Remove from oven and let cool in the Dutch oven a few minutes before serving.