Place the dried beans in a large bowl and cover with cold water. You want enough water to cover by about 3 inches because the beans will swell. Let sit for 8 hours or overnight.
Bring to a boil, stirring occasionally, then reduce heat to medium and continue cooking for 90 minutes, uncovered, stirring every 20 minutes or so.
Drain the beans. Place them in a large, heavy pot. I use a cast iron Dutch oven. Add the broth, onions and bay leaf. You're not adding any other seasonings because your homemade broth should be pretty flavorful. You'll taste for seasoning at the end of cooking.
Reduce heat to medium-low and continue cooking, uncovered, for 2 hours, stirring occasionally, to reduce the liquid and concentrate the flavors.
Reduce heat to low. Using an emersion stick blender or a potato masher (my preference), mash up the cooked beans while they're still in the cooking pot. Might seem like there's too much broth yet, but the beans will absorb more as they're mashed, plus you can cook them down further, if necessary, after mashing. Don't try to mash/blend them perfectly smooth; they're best a bit "lumpy".
Stir in the 10 ounces of extra-sharp cheddar cheese. Taste for seasoning. If you think it needs salt, pepper or garlic powder, stir that in now. If the consistency is not as thick as you like, continue cooking over medium heat, uncovered, stirring, until they reach your desired consistency.
Stir in the diced jalapeo peppers, to taste. I love the flavor, and I also add a bit of the liquid from the jar of jalapeo peppers. Start off with a little bit, stir, taste, and adjust to your preference.
A WORD OF WARNING: All jarred jalapeo pepper slices aren't the same! I used to think they were, until a recent rushed trip to the supermarket taught me otherwise. They were out of the store brand I usually buy, so I grabbed the brand that was there (see photo). Diced a few and stirred them into my beans, along with some of the liquid from the jar, then tasted them for seasoning.
To my horror, they were sweet! I grabbed the jar of peppers and read the ingredients list. Second, right after jalapeos, was high fructose corn syrup! I kid you not! Nasty tasting! DO NOT use these when making this recipe!! Sugar/corn syrup and jalapeos do NOT taste good together!
