Heat butter in a medium-size pot over medium heat. Add onions and cook for 7-10 minutes, stirring occasionally.
Stir in garlic, chipotle chili powder, salt, and smoked paprika; cook for 1-2 minutes.
Add the mustards, the Redpath® Dark Brown Sugar, cider vinegar, and Worcestershire sauce to pot, stirring until sugar is dissolved; about 3-4 minutes. Remove from heat and let cool completely before using.