Heat the oil in a saucepan over medium heat.
Add the chopped onions and cook, stirring often, until the onions are brown. Approximately 10 minutes.
Add the chili powder, ancho chili powder, brown sugar, garlic, cinnamon, and cloves and stir for 1 minutes, until the mix is fragrant.
Add the tomatoes, peanut butter, cocoa powder, and water. Stir to combine.
Reduce the heat to medium-low and cook the sauce, stirring occasionally, for 15 minutes.
Remove from heat and season, to taste, with salt and pepper.