Mushroom and spinach stuffed lamb

I’ve been sick (run down from working too hard) lately, and to make myself feel better I bought new sheets. (It didn’t really work except make me want to be in bed all day long, every day). Look how comfortable Puff looks there! I wish I was her. She gets to sleep all day.
Anyway, another thing I’ve been doing to make myself feel better is cooking nice, fancier meals than I usually do. I bought a butterflied leg of lamb the other day, and stuffed it with mushrooms and spinach and garlic. It was really good. I don’t cook lamb often enough.

Stuffed lamb with mushrooms and spinach

1 butterflied leg of lamb
salt and pepper
about 1/2 pound of mushrooms, diced
1/2 an onion, diced
1 T minced garlic
a few good handfuls of spinach

Preheat your oven to 450. Sautee the mushrooms, garlic, and onion in a pan until softened, about 5 minutes, over medium-low heat. Stir in the spinach, let wilt slightly. Cool slightly, enough to handle (to speed this up you can stick it in the fridge/freezer). Open up the lamb, fatty side down, and sprinkle generously with salt and pepper. Spread the mushroom mixture evenly over the lamb, then carefully roll, tucking and poking filling back in as you go. Tie securely with butcher’s string (you may need another pair of hands for this part) and place in a pan. Sprinkle the outside with salt and pepper, then stick in the oven for 10 minutes. After 10 minutes, turn the heat down to 350 and cook until thermometer reached 125-130 for medium rare in the thickest part of the meat, about an hour. Let rest for 15 minutes.
If you want, you can make a gravy from the pan juices: Melt some butter (or fat) in a pan, then sprinkle about the same amount of sweet rice flour over it. Whisk in, let cook for a minute or two, then whisk in about 1 cup of hot liquid, it can be a combination of juice from the roast and stock, or water, or wine, or milk, or whatever you want. Stir until thickened, taste for salt and pepper.