Place beans in pressure cooker and add enough water to cover beans by at least two inches.
Cook on high heat until pressure cooker top is rocking well. Reduce heat and continue to cook on medium-low for 35 to 40 minutes. If you like your beans with more texture, cook 35 minutes. For extra smooth beans, cook 40 minutes.
When beans are done. Release pressure and steam on your cooker according to manufacturer's directions. Drain and reserve broth. With a masher, mash beans to a smooth consistency, adding back small amounts of bean broth/water as needed. Season with salt to taste.
Heat shortening in skillet and scoop cooked beans into skillet. Cook beans in shortening over medium heat for 3 to 4 minutes.
Preheat oven broiler, and spread beans evenly onto an oven-proof plate(s). (Note: You may use individual plates for each serving, or 1 large plate from which to spoon each serving. Keep in mind that individual serving plates from the broiler will be extremely hot.) Before placing under broiler, sprinkle generously with shredded cheese. Place under broiler for about 1 minute, or until cheese is well-melted.