Bring a large pot of salted water to a boil. Add the halved Brussels sprouts and cook for about 3 to 4 minutes until they are bright green and slightly tender. Drain them immediately and plunge them into a bowl of ice water to stop the cooking process. This keeps them vibrant for your Christmas table.
Reduce the heat to low and pour in the heavy cream. Stir in the smoked paprika, salt, and pepper. Add the blanched Brussels sprouts and the cooked turkey bacon back into the skillet, tossing gently to coat everything in the cream. Stir in half of the Gruyere and half of the Parmesan until the cheese begins to melt and thicken the sauce.
In a small bowl, mix the Panko breadcrumbs with the melted butter and the remaining Parmesan cheese. Sprinkle the remaining Gruyere over the top of the sprouts, then finish with an even layer of the buttery breadcrumbs. Transfer the skillet to a preheated oven at 375 degrees Fahrenheit and bake for 15 to 20 minutes until the top is golden brown and bubbling.