Step 1

Preheat the oven to 400 degrees F.

Step 2

In a small bowl combine panko, Parmesan cheese, lemon zest, salt and pepper. Set aside.

Step 3

In a large cast iron skillet, cook the bacon over medium heat until crispy. Transfer to a plate that has been lined with a paper towel. Set aside.

Step 4

Add the brussels sprouts to the hot pan and cook, stirring occasionally, until crispy and slightly charred. This will take about 5 minutes.

Step 5

Add the red onion, garlic, and thyme to the pan and cook for one minute. Pour in the heavy cream and reduce the heat to low and simmer for 1 to 2 minutes. Season with salt and black pepper, to taste. Stir in the cooked bacon.

Step 6

Sprinkle the brussels sprouts with shredded Gruyere and mozzarella cheese. Top with panko parmesan topping.

Step 7

Bake for 12 to 15 minutes or until bubbly, cheese is melted, and Brussels sprouts are tender but slightly crisp. Turn the oven to broil and broil for 1 to 2 minutes to brown the cheese and topping.

Step 8

Remove from the oven and let sit for 5 to 10 minutes. Season with additional salt and pepper, if necessary. Serve warm.