1/4 teaspoon cayenne pepper, or to taste, optional
Kosher salt, to taste, optional
Crostini, assorted cheeses, and crackers, to serve
Cook bacon in a large, heavy-bottomed skillet over medium heat until the bacon is crispy and the rendered fat begins to foam, about 10 minutes. Transfer the bacon to a paper towel lined baking sheet and discard of all but about 1 tablespoon of the bacon fat.
Return the skillet to medium heat and pour over the onions. Cook until soft and beginning to brown, about 10 minutes.
Add in the brown sugar, apple cider vinegar, coffee, garlic, thyme, smoked paprika, black pepper, and cayenne pepper– if using. Stir and cook until the mixture is a warm brown and somewhat thickened, about 5 minutes.
Finely chop the bacon. Then add the bacon back to the onion mixture and continue to cook until the mixture is dark reddish-brown and is jam-like in consistency, about 10 more minutes. If the mixture dries out as it cooks, add a couple of tablespoons of water at a time, as needed. Taste and season with kosher salt and adjust seasonings, as desired.
Remove from heat. If too chunky or not jam-like, pulse briefly in a food processor or blender. Transfer to a large bowl or jar, garnish with a sprig of thyme, and serve at room temperature with crostini, assorted cheeses, and crackers.