Preheat oven to 375 degrees. Cook pasta according to package directions. Drain and set aside. In the same stock pot, heat butter at medium heat. Once melted and bubbly, whisk in flour. Simmer 1-2 minutes, until golden in color. Slowly whisk in milk, bringing heat to medium-high. Continue to whisk, bringing to a simmer. Whisk in salt, pepper, ground mustard and cayenne pepper. Gently simmer 4-6 minutes, until thickened. Taste and adjust seasoning, if necessary. Remove from heat and whisk in 1 ½ cups sharp cheddar and Gruyere. Stir in cooked pasta and roasted veggies. Coat two 12-cup muffin tins with cooking spray. Fill each cup with mac and cheese and top with remaining sharp cheddar cheese. Bake 12-15 minutes, until cheese is melted and bubbly. Allow to slightly cool, then remove mac and cheese cups from the tin. Top with chopped parsley and serve.