Cook ½ lb of pasta in a large pot of salted boiling water until it’s barely al dente. (It should be a little undercooked – it will cook more in the oven.) Drain and set aside when done.
½ lb pasta
Grate the cheeses – both the mixed and topping cheese. Crush or finely chop the garlic. Measure out the ingredients, since this one requires active cooking/stirring when making the sauce.
Pre-heat the oven to 425ºF.
In a large saucepot (at least 3 qt), melt the butter over medium heat. Whisk in the 2 tbsp flour and cook, whisking constantly for about 4 minutes, until the flour foams and is beginning to turn a light golden brown.
2 tbsp unsalted butter, 2 tbsp all-purpose flour
While still stirring, add the garlic, paprika and cayenne, then season lightly pepper.
1 clove garlic, 1 tsp smoked or hot paprika, ½ tsp cayenne pepper
Slowly whisk in milk to avoid clumping. Keep whisking while it comes to a simmer, making sure the flour mixture on the edges is totally incorporated.
2 cups whole milk
Remove the pan from heat. Add the grated cheese. Whisk to blend until the cheese is completely melted; it will start thick, then thin out. It should be fairly thin - you want to cook and whisk until it coats the back of a spoon like a cold heavy cream. (It will thicken in the oven and once cooled a bit, so it's ok if it seems far too thin here.) Pour into the baking dish.
5 oz cheddar cheese, 5 oz fontina cheese
In a small bowl, add the ½ cup bread crumps, 1 tbsp olive oil and 4 tbsp grated hard cheese. Spread the toping in a thin layer on top.
½ cup course bread crumbs, 1 tbsp olive oil, 4 tbsp Parmesan cheese
Bake for at least 25 minutes, until everything is bubbling, thickened, and creamy, and the bread crumbs are evenly golden brown.