This is simple.
Go to a custom butcher and order UNCUT Sauce. Doesn’t matter what kind, Brats, Italian Sausage etc
Fill a Lasagna pan with the meat and bake it
Drain off the fat and add drops of red food coloring
If you use Italian Sausage you might drip on some spaghetti sauce
If you are making Bratwurst you might drop in some random sauerkraut for the “Maggot look”