(4 servings)
Put the sugar and blueberries in a pot over medium heat. Bring to a boil until the blueberries are cooked and the jam gains consistency (about 15 minutes). Remove from the heat and allow to cool.
Mix the ground beef with minced bacon in a bowl. Add salt, pepper and mustard. Once well mixed, divide into 4 and make the patties. Freeze for 1 hour.
Turn on the grill to high heat. Once very hot, put the patties and let them brown, then flip and cook for about 5 minutes and add a slice of cheese over each patty so it melts.
Brush each bun with melted butter and place them face down on the grill to heat.
Place a patty with melted cheese on each bun base, add lettuce on top and then some blueberry jam.
Top with the other half of bun and serve.
