Add ground meat to a large bowl
Mix together panko bread crumbs and half and half and let soak for 5 minutes
Add soaked bread crumbs, egg, and seasonings to ground meat mix, and mix with your hand until just combined
Heat 1 tablespoon of butter or olive oil in a skillet or multi-cooker
Form meat mixture into ping-pong-sized balls and place in a single layer in skillet or multicooker
Brown meatballs on each side for about 2 minutes, then transfer to slow cooker
Add beef broth, cover, and cook on low for about 6 hours or high for about 3 hours
To make gravy, heat remaining 4 tablespoons of butter in the skillet
Whisk in flour until smooth
Slowly pour in broth from slow cooker and continue to whisk the mixture.
Next, add blackberry preserves and sour cream, and bring gravy to a simmer while continuing to whisk until sauce thickens (about 5 minutes)
Cook noodles according to package directions
Serve meatballs with sauce over noodles and garnish with parsley, if desired