Sausage and Mushroom Penne Gratin

Ingredients

• 1 pound bulk sausage sweet italian
• 1  garlic clove 
• 1 cup heavy cream 
• 1 pound d mushrooms sliced
• 2 tablespoons olive oil divided
• 0.5 cup parmigiano-reggiano grated
• 1 pound penne pasta dried
• 8 ounces whole-milk mozzarella shredded divided

Equipment

• bowl
• frying pan
• pot
• baking pan
• broiler
• slotted spoon

Directions

1. Cook penne in a pasta pot of boiling salted water (2 tablespoons salt for 6 quarts water) until al dente. Reserve 1/2 cup pasta-cooking water, then drain pasta and transfer to a flameproof 3-quart baking dish.
2. Preheat broiler.
3. Meanwhile, cook sausage in 1 tablespoon oil in a 12-inch nonstick skillet over high heat, stirring occasionally and breaking up any large pieces, until no longer pink.
4. Transfer with a slotted spoon to a bowl, leaving fat in skillet.
5. Add remaining tablespoon oil to skillet along with mushrooms and garlic, then cook over high heat, stirring occasionally, until mushrooms are golden, about 3 minutes.
6. Return sausage to skillet along with cream, reserved 1/2 cup cooking water, a rounded 1/4 teaspoon salt, and 1/4 teaspoon pepper and boil over high heat, stirring once or twice, until thickened, about 4 minutes.
7. Pour over pasta, then stir in Parmigiano-Reggiano, 1/2 cup mozzarella, and salt to taste.
8. Spread evenly in baking dish and top with remaining mozzarella.
9. Broil 3 to 4 inches from heat until golden brown in spots, about 5 minutes.
10. a green salad