Preheat oven to 375 degrees.
Bring a large pot of water to a boil with a pinch of salt and a drizzle of olive oil.
Add pasta and boil for amount of minutes indicated on package. Drain and set aside.
In another large pot melt 6 tablespoons of butter. Once melted add in flour and stir until combined and thickened into a paste.
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.
Add pasta to cheese sauce and mix.
Spray a 9x13 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.
Place tomato slices on top of macaroni and cheese (optionaand then sprinkle the breadcrumbs over top.
Bake for about 30 minutes, until bubbling and edges are starting to brown.