Preheat oven to 350 degrees and grease a 3-4 quart baking dish.
Cook the pasta until al dente, drain, coat it with olive oil, and set aside.
To begin preparing the cheese sauce, melt 6 tbsp of butter in a sauce pan or dutch oven.
Whisk in flour gradually over medium low heat about 2 minutes to remove the flour taste.
Gradually add the milk and heavy cream until slightly thickened. Add salt and pepper.
Slowly add 3 cups of cheddar and 1 cup of gruyere and whisk until smooth and thick.
Stir in the cooked pasta.
In the baking dish, pour half of the pasta, the rest of the cheese, then the rest of the pasta.
In a bowl, mix panko, parmesan cheese, 4 tbsp melted butter, and paprika. Sprinkle it over the top.
Bake until golden and bubbly, about 30-35 minutes.