Combine jam ingredients in a small saucepan. Bring to a boil over medium heat, using a wooden spoon to smash blackberries. Reduce heat to low and allow blackberries to simmer 25-30 minutes until reduced and jam-like in texture, stirring occasionally.
Remove jam from heat, allow to cool, and store in refrigerator up to 2 weeks.
Blue Cheese Mayo
In a small bowl, combine all mayo ingredients. Season mayo with salt and pepper to taste and store in refrigerator until ready to use.
Blue Cheese Burgers
In a large bowl, combine ground chuck, blue cheese, garlic, mustard, Worcestershire, salt, and pepper. Gently knead until meat is just combined then divide into 4 portions. Form each portion into a burger patty.
Preheat an outdoor grill to 400F or if cooking indoors, grease a large cast iron grill pan and heat over medium-high heat. Grill burgers flipping once until burgers reach your desired degree of doneness (see blog post for more info on this)
Arrange arugula on bottom half of toasted buns. Top with burger patty, a layer of about 1-2 tablespoons blackberry jam, and a spoonful of blue cheese mayo. Top with top half of buns, serve burgers immediately, and enjoy!
Notes
Storing InstructionsBurgers are best if served immediately after assembly.