Place a 10-inch ovenproof skillet into the oven and heat the oven to 400°F. (heating the skillet in the oven for at least 8 minutes while you prepare the batter).
While the oven is heating, place the eggs, milk, 3 tablespoons soup and the flour into a blender. Cover and blend for 30 seconds or until the mixture is smooth.
Carefully remove the hot skillet from the oven. Add 1 tablespoon oil to the skillet and tilt to coat the bottom with the oil. Pour the batter into the skillet. Return to the oven and bake for 15 minutes or until golden brown and puffed up around the edges.
While the Dutch baby is baking, heat the remaining 1 tablespoon oil in a 12-inch nonstick skillet over medium-high heat. Add the sausage and cook until well browned, stirring often to separate meat. Add the broccoli rabe, onion and red pepper and cook for 8 minutes. Stir in the spinach and remaining soup and cook until the spinach is wilted (stir in 1/4 cup water for thinner consistency, if desired).
Spoon the sausage mixture in the center of the Dutch baby. Sprinkle with the cheese. Bake for another 10 minutes (it will get a little more browned on the edges). Cut into wedges to serve.
The combination of the broccoli rabe and the spinach in the filling is a perfect balance of sharp and mild flavors. If you prefer the more powerful flavor of broccoli rabe, feel free to swap out the spinach!
This nutritional information refers to each serving of the entire recipe and not just the products used as ingredients.