Cajun Chicken Sandwiches

In a small bowl, combine 4 TBSP mayonnaise, 1 TBSP ketchup, 1 tsp hot sauce, 1 tsp water, ½ tsp Blackening Spice, ¼ tsp sugar, and a pinch of salt and pepper. (For 4 servings, use 8 TBSP mayonnaise, 2 TBSP ketchup, 2 tsp hot sauce, 2 tsp water, 1 tsp Blackening Spice, and ½ tsp sugar.)

Pat chicken dry with paper towels; place between two large pieces of plastic wrap. Pound with a mallet or rolling pin until chicken is about ⅓ inch thick. Season all over with remaining Blackening Spice, salt, and pepper. Heat a drizzle of oil in a medium pan over medium-high heat. Add chicken and cook until browned and cooked through, 4-6 minutes per side. (Reduce heat if chicken begins to brown too quickly.) Turn off heat; transfer to a plate to rest. Wipe out pan.

Heat a drizzle of oil in same pan over medium-high heat. Add onion rounds and cook until deeply browned and tender, 2-3 minutes per side. Turn off heat; transfer to a plate. Wipe out pan.

Melt 1 TBSP butter (2 TBSP for 4 servings) in same pan over medium heat. Add buns, cut sides down, to hot pan. Toast until golden brown, 1-2 minutes. (Depending on the size of your pan, you may need to work in batches.)