Spray a foil-covered baking dish with non-stick spray. Place chicken thighs smooth side up and season with salt and pepper. Bake for 15 minutes. Don't worry, it's not supposed to look appetizing at this point.
While the chicken is baking, prepare the BBQ sauce: In a small saucepan, combine the BBQ sauce, hot pepper jelly, and apple cider vinegar. Use a microplane grater to grate the garlic into the sauce. Cook while stirring over low heat for 10 minutes, until the sauce is heated through and the jelly is completely dissolved into the sauce.You are going to be brushing and basting half-cooked chicken with sauce, so I recommend dividing the sauce into two portions - the 'clean' sauce and the sauce for brushing the chicken. You can add to the chicken-contaminated sauce from the clean sauce container as needed.
Back to the chicken! After 15 minutes, remove the baking dish from the oven, and use tongs to carefully flip each chicken thigh. Brush each chicken thigh with BBQ sauce, then flip them back over. Brush the other side with sauce. Place the chicken back into the oven for 7 minutes.
Brush each chicken thigh with more sauce. Back into the oven for 7 minutes.
Remove the chicken from the oven. Turn up the heat to 450F. Brush each chicken thigh with sauce again, and place it back into the oven for 7 minutes. Remove from oven, allow to cool, and enjoy!