Heat oven to 400 degrees F. Poke potatoes all over with a fork. Place directly on center oven rack; bake 50 minutes until potatoes are tender and easily pierced with a fork.

Holding potatoes with an oven mitt or kitchen towel, slice off the top quarter (lengthwise) of each potato. Use a spoon to carefully scoop out the insides into a large bowl, leaving the skins intact.

To the bowl, add 2 tablespoons butter. Mash with a fork or potato masher until butter is incorporated. Add 1/4 cup Asiago cheese, sour cream, half-and-half, 1 tablespoon horseradish, 1/2 tablespoon chives and salt and pepper to taste; stir to combine.

Spoon and mound the potato mixture back into the potato skins. Cut remaining 1/2 tablespoon butter into cubes and place on top of potatoes. Sprinkle tops with remaining 1 tablespoon of Asiago cheese and 1 teaspoon horseradish. Place on a baking sheet or in a baking pan.

Bake 20 minutes until warmed through and tops are golden brown. Sprinkle with remaining 1/2 tablespoon chopped chives just before serving.