Soak the beans overnight. Drain the beans, cover them with water, add the ½ onion and garlic cloves and bring to a boil. Reduce the heat and simmer until cooked through, about 1½ to 2 hours. Discard the onion and garlic and set aside to cool.
Once the beans are cool enough, transfer them to a blender. Puree the beans using the cooking liquid as needed until smooth, then set aside.
Heat the lard in a Dutch oven over medium heat. Sauté the bacon and the chorizo in the lard until crispy. Remove about 1/³ of the lard/oil and discard. Add the diced onion to the pot and sauté for 2 minutes. Add the pureed beans—stirring constantly to prevent them from sticking.
When the mixture starts to boil, add the cheese and the jalapeños. Add the olives and salt, to taste. Serve hot.