Reserve ¼ cup of the buffalo sauce for the meatball mixture. Add 2 the rest of the sauce and the butter to a large skillet and heat over medium until the butter melts, whisking well to make a smooth sauce. Turn off the heat and cover it with a lid.
Preheat the oven to 450°F. In a large bowl, use your hands to gently mix the ground chicken with the reserved ¼ cup of buffalo sauce, the green onion, garlic, celery, eggs, salt and pepper, and breadcrumbs until well combined. Don't overwork the mixture or your meatballs could turn out dry or tough.
Then, use a 2-inch cookie scoop to form all of the meatballs into equal size balls, laying them out in rows on a sheet pan. Next, fill a small bowl with water, dip your hands in, then roll each of the meatballs in the palms of your hands until smooth and uniform, placing them back on the sheet pan as you go. Brush each of the tops with a little oil then bake in the oven for 10 minutes. Raise the heat to 500°F and cook for 5 more minutes to brown the tops.
Warm the buffalo sauce on medium then add the meatballs, tossing to coat. Split the rolls and toast or warm up in the oven. Slather split sides with blue cheese dressing and fill each roll with 3 meatballs. Serve with crumbles of blue cheese on top and more blue cheese dressing if desired.
Notes
Melt a slice of white cheese like provolone or havarti on the rolls if desired. Use any leftover dressing for salads or a dip.