Finely chop 4 slices of the bacon and place in a large bowl. Add beef, panko, Parmesan, egg, parsley, onion, pepper, 1 tablespoon of the garlic, 1 tablespoon of the chipotle chiles, 1 tablespoon of the adobo sauce, 1 tablespoon of the Worcestershire, 1 teaspoon of the chili powder, and 1 teaspoon of the salt; mix with clean hands until well combined. Roll mixture into 24 (about 1 1/4 oz. each) balls; set aside.

Chop remaining 2 slices of bacon and cook in a 12-inch cast-iron skillet over medium, stirring occasionally, until crispy, about 10 minutes. Transfer to a small, paper towel-lined plate, reserving drippings in skillet; set aside.

Heat reserved drippings over medium. Add half of the meatballs, and cook, turning occasionally, until browned on most sides, 6 to 8 minutes (meatballs will not be cooked through). Transfer to a large plate, and repeat with remaining half of meatballs. Set 1 tablespoon of the drippings aside; discard remaining drippings. Wipe skillet clean.

Whisk together stock, molasses, mustard, cornstarch, and remaining 1 tablespoon adobo sauce, 1 tablespoon Worcestershire, and 1/4 teaspoon salt in a liquid measuring cup. Heat reserved 1 tablespoon drippings over medium. Add remaining 1 tablespoon garlic, 1 tablespoon chipotle chiles, and 1 teaspoon chili powder; cook, stirring constantly, until fragrant, about 30 seconds. Add bourbon, and cook, stirring constantly, until almost completely evaporated, 30 seconds to 1 minute. Add stock mixture.

Bring stock mixture to a simmer over medium, then add reserved meatballs; cook over medium-low, gently stirring occasionally, until an instant-read thermometer inserted into thickest part of meatballs registers 160°F, 6 to 8 minutes. Remove from heat, and gently stir in butter, a few pieces at a time, until melted and sauce is smooth. Garnish with parsley and reserved bacon, and serve with rice.