Place potatoes and 1 teaspoon salt in large sauce pan. Cover with water. Bring to boil over high heat and cook 10 minutes or until potatoes are tender when pierced with a fork. Drain potatoes in colander.
In saucepan, mash potatoes with potato masher or fork, or beat with electric hand mixer until chunky.
Heat the milk, butter and Taco seasoning together in a small microwavable bowl in the microwave for 1 minute or until butter is melted.
Add into the mashed potatoes.
Fold into the potatoes the black beans, salsa and half of the pepper jack cheese.
Using an ice cream scoop, scoop the potatoes and fill each cup. Top each with a sprinkle of pepper jack cheese.
Bake uncovered for 20 minutes. Remove from oven, loosen sides with a knife and place on a large platter.
Serve hot with jalapenos and sour cream on the side.
These can be placed in individual foiled muffin paper liners and placed on a buffet.