Preheat the oven to 425°F (220°C). Place chicken thighs on a baking sheet lined with parchment paper. Rub 2 tablespoons of butter over the chicken skin and season with salt, pepper, smoked paprika, chili powder, and cayenne. Roast for 25-30 minutes until skin is crispy and meat is cooked through.
Meanwhile, melt the remaining 2 tablespoons of butter in a skillet over medium heat. Add minced garlic and cook until fragrant, about 1 minute, until fragrant and slightly golden. Add bourbon and cook until alcohol evaporates, about 2 minutes, stirring occasionally.
Stir in smoked paprika, chili powder, and cayenne pepper into the skillet. Cook the mixture, stirring, for about 1-2 minutes until the spices are toasted and smell aromatic. Watch for the mixture to thicken slightly and become glossy.
Once the chicken is done roasting, transfer it to the skillet with the sauce. Use tongs to coat each piece thoroughly in the smoky butter sauce, letting it simmer for 2-3 minutes until the chicken skin is glossy and the sauce is well integrated.
Remove from heat and serve immediately, arranging the chicken on a platter with some of the sauce drizzled over the top. The chicken skin should be browned and crispy, with a shiny, smoky, spicy coating.
