Cheesemonger's Mac and Cheese

This recipe is excerpted/adapted from Bon Appetit that looked good (with a slightly different "twist" than the previously posted recipe).

3/2 cups Gruyere cheese, coarsely grated
3/2 cups sharp chedder cheese, coarsely graed
3/2 cups Brie, rindless and diced*
5 tbsp butter
1/4 cup all-purpose flour
2 tsp fresh thyme, chopped
3/4 tsp nutmeg
4 cups milk, whole
7/4 cups breadcrumbs
1 pound penne pasta

Preheat oven to 375 degrees.
1. Mix all cheeses. Set aside 1 cup for topping; cover and chill.
2. Melt 4 tablespoons butter in large saucepan over medium heat. Add flour and stir until mixture turns golden brown, about 4 minutes. Add thyme and nutmeg. Gradually whisk in milk. Simmer and stir until thickened and smooth, about four minutes. Add cheese and stir until melted and smooth.
3. Melt 1 tbsp butter in heavy skillet over medium-high heat. Add breadcrumbs, toss. Stir until golden, about 2 minutes. Transfer to plate.
4. Cook pasta al dente. Drain and transfer to large bowl. Pour cheese sauce over and toss. Place in baking pan and sprinkle with reserved 1 cup cheese (the original recipes calls for placing in individual custard cups and placing these on a rimmed baking sheet).
5. Cover with foil and bake 15 minutes. Uncover; sprinkle with breadcrumbs and then bake until golden, about 20 minutes.

*tip from recipe: "It's easiest to remove the rind and dice the Brie if you put in the freezer for 15 minutes to firm it up first."

Albert A, Knowlton A, Barnhurst N. 2007. Bon appetit. Small restaurants, big ideas. September:143.