Slow-Cooker Pizza

This recipe is from my "Fix-It and Forget-It" cookbook.  I made it for the first time yesterday and it was a big hit.  It's super easy to make and really yummy.  Sorry that I don't have a picture of it!

INGREDIENTS:
1 1/2 lbs ground beef or bulk Italian sausage (I used Italian sausage and only used a pound because it was all I had)
1 medium onion, chopped
1 green pepper, chopped
Half a box rigatoni, cooked
7-oz jar sliced mushrooms, drained
3-oz. sliced pepperoni
16-oz jar pizza sauce (This didn't seem like it was enough so I added a little spaghetti sauce)
10-oz mozzarella cheese, shredded
10-oz cheddar cheese, shredded

DIRECTIONS:
1. Brown ground beef (or Italian sausage) and onions in saucepan.  Drain.  Meanwhile cook rigatoni as directed on box.
2.  Layer half of each of the following, in the order given, in slow cooker: ground beef and onions, green pepper, noodles, muxhrooms, pepperoni, pizza sauce, cheddar cheese, mozzarella cheese.  Repeat layers. 
3. Cover.  Cook on Low 3-4 hours. 

NOTE:
Keep rigatoni covered with sauce so they don't become dry and crunchy. 

VARIATION:
Add a 10 3/4 oz can of cream of mushroom soup to the mix, putting half of it in as a layer after the first time the noodles appear, and the other half after the second layer of noodles.  (I did this because I wanted to make sure it wasn't too dry)