Rigatoni with Creamy Sausage Sauce

8 oz. uncooked rigatoni
16 oz. Italian sausage
8 oz. mushrooms
1 tbsp. garlic, minced
2 tbsp. flour
1 1/2 c. milk
1 c. frozen peas
1/2 tsp. salt
1/4 tsp. black pepper
1/2 c. roasted red peppers, water-packed, sliced
1/2 c. scallions, sliced (2 bunches)
1/4 c. Parmesan cheese, grated

1. In a large skillet, cook sausage stirring and breaking into chunks until browned. Add mushrooms and sauté until browned and tender. Stir in garlic and cook 30 sec. until fragrant.
2. In a measuring cup, whisk together flour and milk until smooth. Stir into skillet with peas, salt, black pepper, roasted red peppers, and scallions. Bring sauce to a boil; simmer until thickened and peas are tender.
3. Meanwhile, bring a large pot of salted water to a boil. Add pasta and cook according to package directions. Drain pasta; return to pot. Add sausage sauce and cheese; toss to coat.