Mix all aioli ingredients together and store in fridge until ready to use.  This step can be done ahead of time.

Preheat outdoor grill or indoor grill pan. Place ground beef in a mixing bowl. Remove casings from sausage, if necessary, and add to ground beef. Add Italian seasoning, salt, and pepper and use your hands to gently combine.

Divide beef mixture into equal portions, making either 6 small to medium sized burgers or 4 larger ones. Place patties on grill. Cook for 3-4 minutes and then flip and cook an additional 3-4 minutes until cooked through, or until a thermometer registers 165 degrees. In the last minute of cooking, add a couple slices of cheese to each burger.

While cheese is melting, lightly butter buns and place face down on grill to toast, or place under the broiler until golden brown.

Spread aioli on buns and add burger.  Top with 1-2 tablespoons of marinara.  Toss on a couple basil leaves if desired and top with other half of bun.