Preheat the oven to 400°F and cook the cavatappi in boiling water with 1 tablespoon of salt. Cook per the package instructions to "al dente". Drain and keep hot.

In a bowl, add the shredded cheeses and mix them together. Remove 3 oz (1 lightly packed cup) and set aside in a separate bowl.

In a medium saucepan, melt the butter over medium heat., Add the garlic and cook for 1 minute. 

Whisk in the flour and dry mustard and cook for another minute until thickened.

Slowly pour in the warm milk in three additions. Whisk until thickened and smooth before adding the next addition. Stir in the salt and pepper.

Once all the milk is added, turn the heat up to medium high and whisk until the sauce just starts to bubble and thickens to the consistency of half and half.

Take the pan off the heat, then gradually add the 2 cups of cheese in three parts. Whisk until the sauce is smooth after each addition of cheese.

Scoop half of the mac and cheese mixture into a lightly sprayed 8x8” baking dish.

Sprinkle the layer of mac and cheese with the remaining 1 cup of cheese.

Pour the remaining pasta and lobster over the cheese, into the baking dish and top with the Ritz cracker crumbs.

Bake at 400°F for 15-20 minutes until bubbly. Do not overbake.

Remove the mac and cheese from the oven and let sit for 10-15 minutes before serving. The sauce will thicken as it sits.