Preheat & Prep: Preheat your oven to 425°F. Line a quarter or half sheet pan with aluminum foil, then top with parchment paper for easy cleanup.
Whisk Wet Ingredients: In a large bowl, whisk 2 eggs. Add 1 cup of milk and whisk together.
Soak the Oats: Stir in 3/4 cup quick-cooking oats, 2 tsp onion powder, 1 tsp kosher salt, and 1/2 tsp black pepper. Mix well and let it sit for 5–10 minutes so the oats absorb the milk.
Add Meat & Mix: Add 1 lb ground beef and 1/2 lb pork sausage. Mix gently with clean hands until just combined. (Be gentle so the meatloaf stays tender, and make sure the sausage is evenly distributed!) Let the mixture sit for another 5 minutes to absorb remaining moisture.
Shape the Loaf: Transfer to your prepared sheet pan and shape into a loaf roughly 2" high, 5" wide, and 8" long. Keep it at least 2" high (about the height of your pinky finger) and gently flatten the top and sides.
Bake: Bake at 425°F for 15–20 minutes until the edges start to brown. Rotate the pan, lower the oven temperature to 350°F, and continue baking for another 10–20 minutes until the internal temperature reaches 160°F.