Turn crock pot on high.
Brown the ground beef and drain well.
Return the ground beef to the pan and pour sauce in, mix well and remove from heat.
In a bowl beat the egg.
Mix the ricotta cheese, parsley, salt and pepper into the egg.
Cut mozzarella cheese into small cubes.
Spray a 6 or 7 quart crock pot with cooking spray or wipe down with oil to prevent sticking.
Add about 1 ½ cups of sauce and meat into the bottom of the crock pot and spread evenly over the bottom.
Spread a layer of ricotta cheese over the sauce.
Add a layer of uncooked ziti pasta and spread evenly over the ricotta cheese.
Spread a layer of sauce and meat over the pasta.
Repeat layering the pasta, sauce, ricotta cheese and mozzarella cheese until you have filled the crock pot or run out of ingredients being sure to end with a layer of mozzarella cheese as the final layer.
Place the cover on the crock pot and cook on high.
Slow cook for 4 hours or until the pasta is cooked through.
Serve with a side salad and crusty bread.