Your Crew Will Flip For This Insanely Delicious Pulled-Pork Ring

Name: Your Crew Will Flip For This Insanely Delicious Pulled-Pork Ring
Ingredients: 2/3 c. barbecue sauce, plus more for serving; 1 tbsp. apple cider vinegar; 1 tbsp. plus 1 tsp. packed brown sugar, divided; 1/2 tsp. garlic powder; 1/2 tsp. crushed red pepper flakes; 2 c.; 2 (8-oz.) tubes refrigerated Crescents rolls; 1 1/2 c. Monterey Jack; 1/4 medium red onion, thinly sliced; 1/4 c. sliced pepperoncini peppers; 2 tbsp. melted butter; Kosher salt; Freshly ground black pepper