Step 1

Preheat oven to 375 degrees F. Grate cheeses, placing them together in a large bowl. Boil water and prepare pasta according to directions, cooking for 3-4 minutes less than called-for time.

Step 2

Heat a large oven-safe skillet over medium heat. Once hot, add in olive oil and butter, then throw in shallots with a pinch of salt. Stir to coat and cook for 2-3 minutes, until soft. Add in garlic and cook for 30 seconds. Add flour to the skillet then whisk constantly to create a roux. Let cook for 2-3 minutes until golden brown. Pour in milk, stirring continuously for another 1-2 minutes. Add in mascarpone and almost all of the grated cheeses, reserving about 1/2 cup of the grated cheese. Stir continuously until mixture thickens, about 3-4 minutes. Season with salt, pepper and nutmeg, then tasted and season more if desired. Add pasta to the skillet and toss thoroughly to coat.

Step 3

Sprinkle the top of the mixture with remaining cheeses and breadcrumbs. Bake for 30-35 minutes, or until top is golden brown and bubbly. Serve immediately.