Preheat oven to 375°F.
Bring a large pot of water to a boil with a pinch of salt and a drizzle of olive oil. Add pasta and boil according to package directions (al dente if desired). Drain and set aside.
16 oz fusilli pasta, 1 dash salt, 1 drizzle olive oil
In another large pot, melt 6 Tablespoons of butter. Once melted, add in flour and stir until combined and thickened into a paste.
10 Tablespoons butter, ½ cup all-purpose flour
Slowly add milk and whisk until creamy, thick, and smooth. Remove from heat and add cheeses, stirring until melted and smooth. Add salt and pepper to taste.
4 cups whole milk, 4 cups sharp cheddar cheese, shredded, 2 cups Gruyere cheese, shredded, salt and pepper, to taste
Add pasta to cheese sauce and mix. Spray a 9 by 13-inch dish with cooking spray and add macaroni and cheese, smoothing into an even layer.
Melt remaining 4 Tablespoons butter in a medium saute pan over medium heat. Add breadcrumbs and cook until golden, stirring constantly. Remove from pan immediately so they don't continue to brown in the hot pan.
10 Tablespoons butter, 1 cup panko breadcrumbs
Place tomato slices on top of macaroni and cheese (optional) and then sprinkle the breadcrumbs over top.
2 medium tomatoes
Bake for about 30 minutes, until bubbling and edges are starting to brown. Serve and enjoy!