Melt some butter in a large, oven-safe saucepan or skillet over medium heat.
Add the same amount of flour and whisk it in.
Gradually add warmed milk, whisking constantly, until the mixture starts to thicken.
Season with a pinch of salt and pepper.
Add cooked pasta, cubes of Fontina cheese, and grated Parmesan, tossing everything in the warm bechamel sauce.
Top with more Parmesan and a few cubes of butter.
Bake in the oven until the top is bubbling and golden-brown.
Serve immediately.
