Bring a large pot of water to a boil. Add the baby potatoes and cook until fork-tender, about 12–20 minutes depending on size. Let them cool for 5–10 minutes so they’re easier to handle.

Cut each potato in half and scoop out a little from the center.

Put the scooped potato into a medium bowl.

Mash the scooped potato lightly with a fork. Add mayonnaise, Dijon mustard, salt, and pepper, then mash until smooth and creamy.

Spoon the filling into a piping bag, snip off the end, and pipe it into the potato halves.

Sprinkle with fresh chopped parsley and arrange on a platter.