Make Creamy Coleslaw:

Make the creamy coleslaw: In a medium bowl, whisk 1/4 cup mayonnaise, 1 tbsp apple cider vinegar, and 1 tsp sugar until smooth. Toss in 1 cup green cabbage, 1/2 cup purple cabbage, and 1/2 cup shredded carrots. Mix well to coat all vegetables thoroughly. Refrigerate until needed.

Prepare Garlic Sauce:

Prepare the creamy garlic sauce: Combine 1/4 cup mayonnaise, 2 tbsp sour cream, 1 tbsp milk, and 2 minced garlic cloves in a small bowl. Season with a pinch of salt and black pepper to taste. Whisk vigorously until thick and pale. Set aside.

Cook Chipotle Sauce:

Cook the honey chipotle sauce: In a small saucepan over medium heat, mix 1/3 cup honey, 2 tbsp chopped chipotle peppers in adobo, and 1/4 cup ketchup. Bring to a gentle simmer. Let bubble for 3-5 minutes, stirring often, until the sauce turns glossy, dark reddish-brown, and sticky. Remove from heat.

Grill Chicken Thighs:

Grill the chicken thighs: Gently flatten 1.5 lbs chicken thighs to even thickness. Coat with 1 tbsp olive oil, 1 tsp kosher salt, and 1/2 tsp black pepper. Preheat a grill or cast iron grill pan over medium-high heat. Cook chicken for 5-7 minutes per side, until deep golden with lightly charred edges.

Glaze with Sauce:

Glaze the chicken: Move the cooked thighs to a large bowl. Pour the warm honey chipotle sauce over the hot chicken. Toss continuously until all pieces are evenly coated and shiny.

Toast Buns and Assemble:

Toast buns and assemble: Spread 2 tbsp butter on the cut sides of 6 brioche slider buns. Toast face-down on a hot skillet for 1-2 minutes. Place a glazed chicken thigh on each bottom bun. Top with a generous scoop of creamy coleslaw, drizzle heavily with garlic sauce, and cap with the top bun placed slightly askew.