Preheat your oven to 400°F and place a 9-inch cast iron skillet inside so it heats up while the oven warms (about 5 minutes).
Brown the sausage in a large skillet over medium-high heat, breaking it apart with a wooden spoon as it cooks. You want it lightly browned but not fully cooked — about 5 to 6 minutes. Transfer to a bowl and set aside.
Mix your batter. In the same bowl where you browned the sausage (or in a clean large mixing bowl), whisk together the flour, eggs, milk, salt, and pepper until just combined. Don't overmix — lumps are fine.
Layer it up. Add half of the browned sausage to your hot skillet, then pour half the batter on top. Sprinkle with half the cheese. Repeat with the remaining sausage, batter, and cheese. Use a spatula to press everything down gently so layers settle into each other.
Bake for 20 minutes until the edges are golden brown and a toothpick inserted in the center comes out clean (internal temperature should reach about 165°F).
The flip. Let it rest 5 minutes, then run a knife around the edge and carefully invert onto a large plate or cutting board. Slide back into the skillet to finish cooking on the other side for 2-3 more minutes if you want both sides golden.
Serve cut into wedges with a sprinkle of fresh parsley if using. It's delicious hot, warm, or at room temperature.
