These twice-baked potatoes with corned beef are potato jackets stuffed with fluffy mashed potatoes, Cheddar cheese, and corned beef. Perfect for dinner on its own or as a side.
Rub the potatoes with oil and place them on a baking sheet lined with parchment paper or aluminum foil.
Bake until tender when pierced with a knife, 45 to 60 minutes. Let the potatoes rest until they’re cool enough to handle but not completely cool.
Slice off the top 1/3 of each potato lengthwise. Scoop out the fluffy baked potato from the skin into a medium bowl, leaving the peel and about 1/4 inch of the outermost potato intact to create a shell.
Using a handheld potato masher, mash the potatoes until fluffy.
Add the sour cream, corned beef, Cheddar, chives, and milk to the mashed potatoes and combine thoroughly. Stir in the ketchup and relish, if using. Season with salt and pepper to taste.
Spoon the mashed potato and corned beef mixture into the baked potato shells and place them on a baking sheet.
Bake until the potatoes are slightly browned and crisp on top and the filling is completely heated through, 10 to 20 minutes.