Preheat the grill to high heat.

Portion the ground beef into 6 equal parts.

Form each portion into a hamburger patty, making a slight indention in the center to prevent bulging.

Season both sides of the patties with salt and pepper.

Slice the watermelon into 1/3-inch thick slices.

Use a biscuit cutter to cut circular shapes from the watermelon slices.

Place the hamburger patties on the preheated grill.

Grill the hamburgers for 3-5 minutes per side, or until cooked to desired doneness.

Approximately 1 minute before removing the patties from the grill, add a slice of Fontina cheese to the top of each patty.

Allow the cheese to melt slightly.

Remove the burgers from the grill and tent them with foil to keep warm.

Place the hamburger buns on the grill.

Toast the buns for 30-60 seconds, or until char marks form.

Remove the buns from the grill.

To assemble the burgers, layer the bottom bun with 2 large basil leaves.

Place a watermelon circle on top of the basil leaves.

Add the cooked patty with melted cheese on top of the watermelon.

Top the patty with a generous spoonful of salsa verde.

Cover with the top bun and serve immediately.