Mix the achiote paste and dried spices together before stirring in the liquid ingredients. Add the chicken thighs to a large dish, cover in the marinade, and refrigerate for at least 3 hours.

When ready to cook, cut the bottoms of the pineapples, about 2" from the bottom. Stick a skewer through the center of each pineapple base. Place the pineapple bases on a rimmed sheet pan lined with foil or parchment paper.

Place the chicken on the skewers, staggering the direction of each piece to create even layers.

Once all the chicken is on the skewers, cut the tops off both pineapples and place a 2" to 3" piece on top of the chicken. Brush with marinade.

Bake on the bottom rack in your oven for 2.5-3 hours at 350ºF or until the chicken reaches 165ºF. Brush some of the rendered fat on the chicken and pineapple in the final 30-60 minutes.

Optional: About an hour into baking, dice the remaining pineapple and place on skewers. Brush with remaining marinade and place across a quarter sheet pan to bake for the remaining time.

Once cooked, use a knife to carve chicken and pineapple off the skewers for tacos.