Preheat the oven to 350 degrees F. Lightly grease a 3-quart casserole dish and set aside.

In a large skillet, melt 1 1/2 tablespoons of the butter over medium-high heat. Add the onions, reduce the heat to medium, and cook, stirring, until soft and lightly caramelized, about 15 minutes.

In a medium skillet, melt the remaining 1/2 tablespoon butter over medium-high heat. Add the Canadian bacon and cook, stirring, for 3 minutes. Drain on paper towels. Add the sausage to the skillet and cook, stirring, until browned, about 5 minutes. Drain on paper towels.

In a large bowl, beat the eggs. Add the milk, cream, salt, Essence, and pepper and whisk to combine. Add the croissants and let sit for 5 minutes. Add the sausage, bacon, onions, Fontina cheese, stir together, and let sit for 5 to 10 minutes. Pour into the prepared dish and bake until almost completely set, 35 to 45 minutes. Cover with aluminum foil if it's browning too much.

In a small bowl, combine the bread crumbs, Parmesan, and melted butter. Uncover the pudding and evenly cover with the bread crumb mixture. Return to the oven, increase the heat to 375 degrees F and bake until completely set in the center and golden brown on top, about 15 minutes.

Serve hot.