In a medium saucepan over medium heat, cook bacon until crispy. Transfer bacon to a paper towel-lined plate, reserving about a tablespoon of bacon fat in the pan.
Reduce heat to medium-low. Add onion and shallots to the pan and cook, stirring often, until the onions are caramelized, about 15 minutes.
Stir in garlic, brown sugar, maple syrup, vinegar, chili powder and cooked bacon. Bring mixture to a simmer then reduce heat to low. Cook until liquid has reduced and thickened and onions are the consistency of jam, about 7-10 minutes.
Let cool before transferring to a jar. Serve with cheese and crackers or as a topping on a hamburger. Store in the refrigerator for up to 2 weeks or freeze. Makes about 1 cup.
Approximate Nutrient Analysis per Tablespoon serving:
70 calories, 3 g fat, 0 g saturated fat, 5 mg cholesterol, 120 mg sodium, 8 g carbohydrate, 0 g fiber, 7 g sugar, 2 g protein