Preparation

• Preheat the oven to 375°F. Butter a 2-quart baking dish.
• In a medium bowl, combine half the crushed crackers with half the parmesan.
• In a large nonstick skillet, melt 2 tablespoons of the butter over medium heat. Pour the melted butter over the cracker mixture and stir to combine. Reserve for the topping.
• In the same skillet, melt the remaining 4 tablespoons butter over medium heat. Add the onions, pepper, and 1 teaspoon of the salt, and cook, stirring frequently, until softened and translucent, about 10 to 12 minutes.
• Transfer the onions to a large bowl and let cool for 5 minutes.
• In a large measuring cup, whisk together the heavy cream, eggs, and remaining 1 teaspoon salt.
• Add the egg mixture to the onions, along with 1 ½ cups of the cheddar cheese, the remaining crushed crackers, and the remaining parmesan. Toss to combine.
• Spoon the mixture into the prepared baking dish and top with the remaining ½ cup cheddar cheese and reserved cracker mixture.
• Bake until golden brown and bubbling, about 30 to 35 minutes.
• Let the casserole sit for 5 minutes before serving.