French Onion Mac & Cheese

Preheat oven to 400℉.
Heat a large skillet over medium-low heat. Add the olive oil and diced onions. Cook slowly to caramelize the onions. Make sure to stir occasionally.
Once onions start to caramelize, add salt. Keep cooking low and slow; stirring occasionally.
Cook macaroni according to package directions. Set aside.
In a separate deep skillet, melt the butter over medium heat. Whisk in the flour until fully incorporated making sure there are no lumps.
Slowly whisk in the heavy cream.
Add the salt and cheeses. Mix until cheese is fully melted. Add the milk and stir to incorporate.
Add the caramelized onions (Optional: reserve some for later to top onto mac and cheese along with breadcrumbs) and macaroni noodles. Stir well.
Transfer the mac & cheese to a lightly greased 11" oval baker or 9"x9" square dish. Optional: top with reserved caramelized onions and spread it out.
Top with breadcrumbs. Bake for 20 minutes.
Serve and enjoy!