Combine the flour, sugar and salt together in the bowl of a food processor, and pulse until just combined. Add the cubed butter and continue to pulse until the butter is pea-sized, but not fully incorporated. Place the dough mixture into a bowl. In a separate bowl, whisk the egg and milk; then add it to the flour mixture. Combine by hand until the mixture just starts to come together, kneading very lightly if necessary. Wrap the dough in plastic wrap and allow it to rest in the refrigerator for 20 minutes before using.
Whisk together the powdered sugar and milk until smooth, adding any additional milk or powdered sugar to achieve desired consistency. Add yellow gel color to reach desired shade of yellow. Set aside.
Divide the Pastry Dough in half and roll one half out to 1/8 inch/.3 cm thickness, keeping it as square as possible. Cut into 2.5 in/6.4 cm by 1.5 in/3.8 cm squares. Repeat with the remaining half of the dough. Place half of the squares on a half sheet pan, lined with parchment paper, and spray them lightly with egg wash spray. Pipe a small amount of the marmalade in the center of each square leaving a half-inch border on all sides. Place a lollipop stick into the piped marmalade. Top each square with the reserved dough square, using a fork to crimp and seal the sides. Bake at 350ºF/176ºC for 12 to 15 minutes, or until golden brown. Allow the pop tarts to cool completely. Decorate with Yellow Icing as desired. Allow the icing to set at room temperature for at least 10 minutes before serving.
