Ingredients:
5 tbsp. butter
1 tbsp. garlic, minced
6 large Bermuda onions, thinly sliced
3 large red onions, thinly sliced
3 medium leeks, sliced, well rinsed and dried
1 tsp. Kosher salt
A few turns of freshly ground pepper
2 cups plain Havarti cheese, grated
3 packages Boursin cheese (5-oz. packages)
2 cups Gruyere cheese, grated
¾ cup dry white wine

Directions: 
Preheat oven to 350°.
Butter a 12-cup baking dish with 2 tbsp. Butter, then spread garlic all over the buttered pan.
Make the first onion layer using a third each of the onions and leeks.
Season onions with a sprinkle of salt and a little pepper. Add Havarti.
A third more each of the onions and leeks, season, add Boursin.
Layer remaining onions and leeks and top with Gruyere.
Dot the top with remaining butter. Can be refrigerated, tightly covered, for up to 24 hours at this point.
Pour wine over everything and bake for 1 hour. Cover with foil if it starts to get too brown. Serve immediately.