Arrange the chicken thighs in a single layer in a 9x13 baking dish.
Scatter the sliced onion over the chicken and drizzle with 2 tablespoons of olive oil.
Sprinkle the adobo, paprika, salt, garlic powder, and onion powder over the top. Using your hands, mix everything together until well combined.
Gently pull back the skin on each chicken thigh and stuff with 3-5 onion slices, then press the skin back into place.
Cover the dish tightly with foil and bake for 45 minutes.
While the chicken bakes, make the sauce: in a small saucepan over medium-low heat, combine the BBQ sauce, honey, brown sugar, and minced garlic. Stir well and bring to a simmer.
Once simmering, whisk in the grape jelly and stir until fully melted and smooth. Remove from the heat.
After 45 minutes, check the internal temperature of the chicken. Once it reaches 165°F, carefully remove the dish from the oven.
Baste each chicken thigh generously with the sauce.
Return the dish to the oven and broil on low for 5-10 minutes, watching closely starting at the 5-minute mark so it doesn't burn.
Remove from the oven and serve.
Video
Notes
Storage: Let the chicken cool completely, then transfer to an airtight container and refrigerate for up to 4 days.Freezing: Freeze in a freezer-safe, airtight container for up to 3 months. Thaw overnight in the refrigerator before reheating.Reheating: Warm covered in a 350°F oven for 15-20 minutes, or microwave in 30-second bursts until heated through. A splash of extra sauce or water helps keep the chicken moist.