Spray crock pot insert with non-stick cooking spray for easier cleanup.
Brown sausage on all sides.
Add soup, tomatoes, onion powder, oregano, and about half a soup can of water to slow cooker and stir to combine. Add browned sausage to slow cooker. Cook on low 5 hours, stirring occasionally, draining water from condensed steam off lid before replacing. Leave the lid off for the last half hour to let the sauce thicken.
Boil penne according to package directions. While pasta is cooking, remove sausages and cut into coins. Add butter to crock and stir to melt. Taste for salt and add if desired. Return sausage to crock pot. Add drained cooked pasta to the crock and stir to combine. Enjoy!