INGREDIENTS
4 cups
elbow macaroni
5 tbsp
unsalted butter
4 cups
milk
1/2
medium onion, stuck with 1 clove
4 cloves
garlic
1
bay leaf
3
sprigs fresh thyme
1 tsp
dry mustard
2 tbsp
all-purpose flour
2 cups
grated Cheddar, plus 1 cup in big chunks
1/2 cup
grated Parmesan
Kosher salt and freshly ground black pepper