These corned beef puffs were developed by the chefs in our test kitchens, and they're perfect for St. Patrick's Day or any other festive occasion when you need to have a few passed hors d'oeuvres around for guests to enjoy.
Preheat the oven to 375 degrees.
Lightly dust a work surface with flour. Roll out the crescent dough to an 11-by-14-inch rectangle and place on top of a 24-cup muffin pan. Use a pastry cutter with straight wheel or a plastic knife to slice the dough crosswise and lengthwise between cups to make 24 squares.
To make the filling, in a bowl, combine the corned beef, scallions, Swiss cheese, mayonnaise, and Dijon mustard. Fill each cup with 1 ½ tablespoons of filling. Bring corners of dough up to the center of each cup. Bake until golden brown, 11-13 minutes.