Soak the white beans overnight in double their volume of water. Drain.
Heat the oil over high heat in a heavy bottomed stock pot. Add the chicken and brown on both sides, about 2 minutes per side. Set aside.
Reduce heat to medium and sauté the onion until soft and slightly browned, 5-7 minutes. Add the chipotle peppers and tomato paste and cook until fragrant. Add the beans and 3 cups of water. Add the frozen purée. Reduce heat to low and allow to simmer, stirring occasionally, until the beans are cooked through, about 40 minutes to an hour.
When the beans are nearly done but still have a bit of bite left to them, add the chicken back into the pot along with the thyme and salt. Cook 20 minutes, until the chicken is cooked through. Remove the chicken and shred with two forks, then add back to the pot.
This is best served the next day after a rest in the fridge. It’s also the perfect thing to have on hand when the afternoons get cold and you want to come home to a hot dinner.