Cut off the tops of the peppers and remove the seeds.
Drain the liquid from 1 of the cans of the tomatoes into a bowl and set the bowl aside.
Combine the ground beef, rice, onion, garlic, drained can of tomatoes, salt and pepper and mix well.
Use the meat mixture to stuff the peppers and place it in a slow cooker.
Add the remaining can of tomatoes to the bowl containing the other liquid.
Add in the tomato paste and the brown sugar and stir to mix well.
Pour over peppers.
Cook on low 6-8 hours.