Step 1

Bake potatoes as directed; let stand about 10 minutes. Cut a lengthwise slice off the top of each baked potato; discard skin from slices and place pulp in a bowl. Scoop out potato pulp; add to the bowl.

Step 2

Mash the potato pulp with a potato masher or an electric mixer on low speed. Add sour cream, garlic salt, and pepper; beat until smooth. (If necessary, stir in 1 to 2 tablespoons milk to reach desired consistency.) Season to taste with salt and additional black pepper. Stir in 1/2 cup of the cheddar cheese and, if desired, chives. Spoon the mashed potato mixture into the potato shells. Place in a 2-quart baking dish.

Step 3

Bake, uncovered, in a 425°F oven for 20 to 25 minutes or until light brown. Sprinkle with remaining cheese. Bake for 2 to 3 minutes more or until cheese melts.