Preheat oven to 375 degrees.

Separate 1/2 cup of Gruyere and 1/2 white cheddar. Reserve.

In a large pot, boil the water over high heat, add salt, drizzle some olive oil and cook the macaroni according to package instructions.

Drain and transfer to a large oven proof dish.

Bring that same pot back to the stove and, over medium high heat, melt the butter. Once the butter is melted, add the flour and whisk until well incorporated, making a roux. Add the milk, slowly, whisking constantly. Keep whisking for about 5 minutes until the sauce boils and thickens. Once it’s thick, add the half and half and cook for a little while longer to almost get thick again. Remove from the heat and add the salt, the pepper, the pinch of nutmeg and the majority of the white cheddar and Gruyere. Mix everything together until well incorporated.

Pour the sauce into the macaroni and stir. Top with the 1/2 cup of Gruyere and the 1/2 white cheddar. Grate some Parmigiano Reggiano on top, to taste. Sprinkle the breadcrumbs and bring it to the oven.

Bake for about 20 minutes or until the top is golden brown and the sauce is bubbly.