Preheat oven to 375°. Using a permanent marker and a 23⁄4-inch round cutter as a guide, draw 15 circles onto 2 sheets of parchment paper. Turn parchment over, and place on 2 baking sheets.
In a medium saucepan, melt butter over medium heat. Add 1⁄2 cup water, milk, granulated sugar, and salt; bring to a boil. Using a wooden spoon, stir in flour. Cook, stirring constantly, until a skin forms on bottom of pan, 1 to 2 minutes. Transfer mixture to the bowl of a stand mixer fitted with the paddle attachment. With mixer on low speed, beat until dough is warm to the touch, about 1 minute. Add eggs and egg white, one at a time, beating until combined.
Transfer batter to a piping bag fitted with a ½-inch round tip (Wilton 2A). Hold tip perpendicular ½ inch above parchment in center of one drawn circle in prepared pan. Holding tip stationary the entire time, pipe batter onto parchment, applying even pressure until batter almost reaches edges of drawn circle. Stop applying pressure and lift. Wet your finger with water and press down the peak in the batter to create a smooth top. Repeat with remaining batter and drawn circles on prepared pans.
Bake for 15 minutes. Rotate pans, and bake until fully puffed and deep golden brown, about 10 minutes more. Let cool completely on wire racks.
Using a serrated knife, cut off top of each cream puff, and reserve. Spoon 2 tablespoons Raspberry Sauce into the center of each cream puff. Using a large round tip (Wilton 2A), pipe Mascarpone Cream on sauce. Top with reserved tops. Garnish with raspberries and confectioners’ sugar, if desired. Serve immediately or same day, refrigerating until ready to serve.
Recipe by Southern Lady Magazine at https://southernladymagazine.com/raspberry-cream-puffs-recipe/