Preheat oven to 400ºF.
Pierce potatoes several times with fork then place them directly on the oven rack and bake them for about 50 minutes, or until they’re easily pierced with a knife.
Remove the potatoes from the oven and transfer them to a rack to cool. Set the oven to broil.
Once the potatoes are cool enough to handle, slice them in half length-wise and use a spoon to scoop out the flesh, leaving about a 1/4-inch ring around each potato. (Reserve flesh for another use, such as gnocchi or mashed potatoes.)
Brush both sides of the potato skins with melted butter and season with salt and pepper. Position the skins, skin side up, on a cookie sheet. Broil for 2 minutes, flip, then broil an additional 2 minutes. (Watch the skins carefully to ensure they don’t burn.) Remove the skins from the oven.
Sauté the chorizo in a large, non-stick frying pan set over medium-low heat, using a wooden spatula or spoon to break it up into smaller pieces, for about 10 minutes or until it’s fully cooked. Use a slotted spoon to portion out the cooked chorizo into the prepared potato skins. Top each potato skin with 2 tablespoons cheese and broil for 4 to 5 minutes, or until the cheese has fully melted.
Remove the potato skins from the oven and garnish with sour cream and chopped chives. Serve immediately.