Put margarine and sausage into the baking dish and place in the oven to heat about 5 minutes before you add the batter. Keep a close eye on it because it will burn if you let it.
Blend eggs, milk, salt, and pepper in a blender or with a mixer. Add the flour 1/4c at a time until just incorporated evenly (don't overmix otherwise you'll activate the gluten in the flour and have a thick dutch baby rather than a fluffy one).
Add batter immediately after it's ready to hot baking dish.
Sprinkle cheese over the batter and bake for 20-25 minutes, until puffy and Golden brown.
Let it cool a few minutes before cutting- it will deflate during this period.
Note: this is my family recipe, and it was is told to me as a ratio- 1/4 milk & flour for every egg- feel free to go up or down a size on your baking dish just adjusting according to the ratio!