Place an 8" cast-iron skillet in oven, and preheat oven to 350℉.
Place all ingredients in a large bowl and mix to combine. Your hands will work best!
Remove cast-iron skillet from oven and carefully place meat mixture into skillet. Press down so it fills the skillet evenly. Bake for 15 minutes.
Prepare the glaze by mixing ketchup and mustard together in a small bowl. After meatloaf has cooked for 15 minutes, spread glaze on top of meatloaf with spatula or brush and bake for an additional 5 minutes.
Cut into 6-8 wedges and enjoy!