Preheat oven to 350°F
In a large pan, heat olive oil over medium heat. Add onions and season with salt to taste. Cook for about 30 minutes until golden brown, stirring frequently. Set aside when done.
In a large saucepan, melt 2 tbsp. butter over medium height. Once butter is melted, add in flour and whisk for 1 minute. Gradually pour in the milk, whisking until combined. Whisk in French Onion Dip until smooth. Let sauce simmer to slightly thicken, about 5 minutes. Stir in Gouda, Monterrey Jack, and 1 cup of sharp white cheddar. Once melted, season with salt and pepper. Mix in onions and cooked pasta.
In a bowl, melt remaining butter and mix in breadcrumbs and 1 cup of white cheddar cheese.
Pour your noodle mixture into a sprayed baking dish and top with breadcrumbs. Bake for about 30 minutes, until golden brown.