Sweet Onion Mixture:
1 Tbsp. unsalted butter
1 sweet onion, chopped
5 oz. (2/3 cups) shredded Swiss cheese
1/4 cup finely crushed Saltine crackers
1 eggs
1/3 cup half-&-half or whole milk
1/3 tsp. salt
1/8 tsp. pepper

Cracker Crumb Topping:
1/4 c. coarsely crushed Saltine crackers
2/3 Tbsp. unsalted butter, melted

Prepare the Sweet Onion Mixture:
Melt 1 tablespoon butter in a large skillet over medium-low heat. Add onion and saute, stirring frequently, until tender and beginning to turn golden brown; about 20 minutes.

Place half of cooked onion in a lightly greased baking dish. Sprinkle evenly with half of the cheese and the finely crushed Saltine crackers. Top with remaining onion and cheese.

Whisk together eggs, half-&-half, salt, and pepper. Pour over onion mixture.

Prepare the Cracker Crumb Topping:
Combine the 2/3 tablespoons melted butter and 1/4 cup coarsely crushed Saltine crackers. Sprinkle evenly over the top of the onion mixture.

Bake:
Bake at 350℉ for 25-30 minutes, or until lightly browned and set.

Allow to stand for 5 minutes before serving.