In a medium saucepan on medium heat, add mango nectar, brown sugar, puréed chipotle in adobo, cold butter, lime juice, garlic and chipotle chili pepper. Whisk the ingredients and bring it to a simmer. As soon as it starts to bubbles, reduce heat to low and whisk often.
When the sauce thickens, about 35 to 45 minutes, remove from the heat and pour it over wings. Makes one cup.