This is a variation of a recipe I found online. I modified it to be more like my mom's version of this dish. She didn't use a slow cooker, but it worked just the same.
1-2 large yellow onions, chopped finely
1 bell pepper, chopped finely
2 lbs. ground beef
3-4 cups of water
2 cans of tomato sauce
2 cans of diced tomatoes
1 box of regular macaroni
3 bay leaves
Healthy smidge of Penzey's Northwoods seasoning
Smoked paprika to taste
Cayenne pepper to taste
Salt and pepper to taste
Saute the onions and pepper in a bit of olive oil until that mixture is well cooked over medium-high heat. Add in the ground beef and brown it with the aromatics. While that all is cooking, dump the water, sauce, tomatoes, and seasoning into the slow cooker on high heat.
Once the ground beef mixture is browned, add that into the mix along with the macaroni. Cook on high for an hour-hour-and-a-half while stirring occasionally.