Mix the Eggs, Mayo, and Cream: In a mixing bowl, whisk together the mayonnaise, heavy cream, and eggs. This creamy mixture will bind the casserole together and add a rich texture.
Add Seasoning: Stir in the mustard powder (or yellow mustard) and a pinch of salt and pepper.
Step 3: Assemble the Casserole
Layer the Ingredients: In a greased 9×13-inch baking dish, spread the cooked ground beef and onion mixture evenly across the bottom.
Top with Bacon and Cheese: Sprinkle the crispy bacon pieces over the beef layer, then add 1 cup of the shredded cheddar cheese.
Pour the Creamy Mixture: Pour the mayonnaise, cream, and egg mixture over the meat and cheese layers, spreading it out to cover evenly.
Add More Cheese: Sprinkle the remaining 1/2 cup of cheese on top for an extra cheesy finish.
