Step 1

Pre-heat oven to 400°.

Step 2

Cook beef and onion in a large skillet with the mustard powder until the meat is browned and the onion is translucent. Drain out the grease and pour the mixture into a 9-inch greased pie pan, spreading it out until it’s an even layer.

Step 3

Sprinkle cheeses over the meat and onion mixture.

Step 4

In a medium bowl, whisk together milk, half and half, onion soup mix, Bisquick, salt and pepper, mustard powder, and eggs. Pour this mixture on top of the cheese.

Step 5

Bake for 25 minutes and cool before serving.