One-Pot Manchego Mac and Cheese with Pimentón Bread Crumbs

Name: One-Pot Manchego Mac and Cheese with Pimentón Bread Crumbs
Cuisine: American
Ingredients: 5 Tbsp. unsalted butter, divided; 2 garlic cloves, finely chopped; 2 tsp. smoked Spanish paprika (pimentón), divided; 1 cup panko breadcrumbs; 1 tsp. kosher salt, plus more to taste; 4 cups whole milk, plus more as needed; 1 lb. dried fusilli pasta, or other pasta with grooves; 2½ cups grated block white American cheese (10 oz.), such as Land O’Lakes; 2½ cups grated manchego cheese (10 oz.); 1½ tsp. mustard powder, or 1 Tbsp. Dijon mustard; Finely chopped parsley leaves, for garnish