Pizza Mac Cheese

Name: Pizza Mac & Cheese
Ingredients: 16 oz. macaroni or shells; 3 tbsp. butter; 3 tbsp. all-purpose flour; 2.5 c. milk; 1.333 c. shredded mozzarella; 0.5 c. shredded fontina; 0.5 c. grated Parmesan, plus more for garnish; 1 c. chopped pepperoni, plus 15 whole slices for topping; 0.75 c. pizza sauce; 1 tbsp. dried oregano; 1 tsp. crushed red pepper flakes