For the Caramelized Onions: Melt butter in a large pot over medium, then add 2 tablespoons of olive oil. Add sliced onions to the pot and sauté onions for 5-7 minutes, until they begin to soften and brown. Season salt and brown sugar.
Add one cup of water to the onions; allow the water to cook until it has completely evaporated - about 20 minutes. The onions should be browned and soft.
Add the mushrooms to the pot with the thyme and continue to cook for another 5 minutes, until the mushrooms have softened.
For the Mac and Cheese: Add Barilla Elbow Pasta to the pot with the mushrooms and onions along with beef broth and evaporated milk. Bring to a slight boil; reduce the heat to a simmer and cover with a lid. Simmer for 10-15 minutes until the pasta is fully cooked. Add the Dijon mustard, grated gruyere, mozzarella, and white cheddar cheese.
Mix everything together until the cheeses are completely melted, then add the garlic powder, onion powder, kosher salt, and black pepper.
