Soak beans overnight, then drain and rinse. Place in a pot, cover with 2 inches of water, and boil. Reduce to a simmer and cook until very tender, 1 to 2 hours. Reserve 2 cups of bean broth, then drain.

In a large skillet over medium heat, melt the lard. Add the onion and cook until translucent and just starting to turn golden, about 5 minutes. Add the garlic and cook 1 minute.

Add the drained beans and a ladle of bean broth to the skillet. Mash with a potato masher over medium heat, adding more broth gradually until the beans reach your preferred creamy consistency, about 10 minutes.

Remove from heat, stir in 1 teaspoon salt, taste, and add the remaining ½ teaspoon salt if needed. Spoon into a bowl, drizzle with a little extra lard or top with crumbled cheese, and serve hot.