Bring a large pot of salted water to a boil. Cook the macaroni two minutes less than what the package directions dictate. Drain and reserve.
1
Melt butter in the pot over medium heat. Whisk in flour. Continue to whisk constantly for two to three minutes. In the last 30 seconds, add garlic.
2
Pour in milk and heavy cream, whisking constantly to create a smooth mixture. Stir in Dijon mustard, salt, pepper and nutmeg. Bring to a simmer.
3
Turn off the heat. Stir in Gruyere and cheddar until melted, and then stir in the pumpkin purée until it becomes one cohesive mixture.
4
Once the cheese fully melts to make one cohesive mixture, added the reserved macaroni. Stir to coat the pasta.
5
Pour the macaroni into a baking dish and top with crushed Ritz crackers and melted butter. Bake until hot and bubbly.
6