2cupsmilk(whole milk or 2% recommended, but any milk will work)
For the topping:
4mediumyellow onions,sliced thin
1tablespoonextra virgin olive oil
2tablespoonsdry white wine
Cook pasta according to package directions.
In a medium saute pan add butter, olive oil, onions and thyme over medium-low heat. Saute, stirring occasionally. After about 15 minutes stir in white wine to deglaze the pan. Continue to caramelize the onions until they are golden brown in color (approximately 20-30 minutes total cooking time). Remove thyme stems and set onions aside.
Add butter and flour to a medium sauce pan on medium heat. Whisk constantly until a paste forms. Slowly pour in your milk while whisking constantly. Bring sauce to a boil.
Mix in the cheeses, garlic, salt and nutmeg while stirring with a rubber spatula or wooden spoon. When all the cheese has melted and the sauce is smooth remove from heat.
In a large bowl or pan mix cooked pasta together with the cheese sauce. Pour macaroni into a large casserole dish.
Top with caramelized onions. Crumble croutons over the top of the onions. Bake at 350 degrees F for 20 minutes until the top has browned and the cheese is bubbling.