Preheat oven to 400 degrees F. Rub the bottom of a gratin dish with the garlic and then discard. Lavishly butter the bottom of the gratin dish with 2 tablespoons of the butter. In a pot of salted boiling water cook the leeks and potatoes for 5 minutes. If you are using dried pasta, add it to the pot and cook for 5 minutes or until it is almost cooked, but not thoroughly. (If you are using a fresh dough, then cook for 2 minutes only. Pasta must remain firm because it continues to cook in the oven). Drain the potatoes, leeks and pasta and divide in two. Place half in the bottom of baking dish and season with salt and pepper. Dot with 2 tablespoons butter, half of Fontina cheese and half of Parmesan. Layer with remaining pasta, potatoes and leeks. Season with salt and pepper and top with Fontina and Parmesan. Dot with remaining butter and bake for 5 minutes only, until cheeses have melted and dish is bubbling hot. Serve immediately.