In a large bowl combine ⅔ cup green onion, ⅓ cup whiskey, bread crumbs, 2 tbs Worcestershire, melted butter, 2 minced garlic cloves, seasoning salt, red pepper flakes, and ground pepper in a bowl with the ground beef and pork.
Shape into 16 patties.
Make the cheddar-whiskey filling: In a food processor combine the cheddar cheese, ⅓ cup green onions, 2 tbs whiskey, 1 ½ teas Worcestershire, and 2 minced garlic cloves.
Pulse until nearly smooth.
Place 1 tbs of the cheddar filling in the center of 8 patties.
Top with the remaining patties and pinch together the sides.
Preheat grill to medium heat.
Place patties on grill, cover and cook for 10 minutes.
Flip each patty, cover and cook an additional 5 minutes.
Open grill and top each burger with the remaining cheese mixture (I just used slices), cover and continue to cook for 5 minutes more.
Spread barbecue sauce over buns, layer on a burger and desired toppings and serve.