Preheat your oven to 350°F (175°C).

In a skillet over medium heat, cook the bacon until crisp. Once cooked, remove from the skillet and drain on a paper towel, then chop it into pieces.

In the same skillet, using the fat from the bacon, add the ground beef and cook until browned, breaking it up with a spoon.

In a large mixing bowl, combine the heavy cream, eggs, mustard, salt, and pepper. Whisk until smooth, then add in the browned beef and bacon, along with half the shredded cheese.

Grease a 9x9-inch baking dish and pour the mixture into the dish, spreading it evenly.

Sprinkle the remaining cheese on top.

Place the dish in the oven and bake for 20 minutes, or until the casserole is set and the cheese is bubbling.