Preheat the oven to 350°F (175°C).

In a saucepan, melt the butter over medium heat.

Add the minced garlic and cook for 4-5 minutes until fragrant.

Add the ketchup, chili sauce, brown sugar, chopped onion, Worcestershire sauce, mustard, celery seed, salt, and Tabasco sauce (if using) to the saucepan.

Bring the mixture to a boil, then reduce the heat and simmer for 5 minutes, stirring occasionally.

Arrange the chicken thighs in a single layer in a shallow baking pan.

Pour the boiling sauce over the chicken, ensuring it is evenly coated.

Place the lemon slices on top of the chicken.

Bake in the preheated oven for 1 hour, basting the chicken with the sauce every 15 minutes.

If desired, uncover the chicken during the last 20 minutes of baking for a crispier skin.

Once cooked through and golden brown, remove from the oven and let it rest for a few minutes before serving.