• Preheat oven to 350°F.
• Cut two pieces of parchment to fit your baking sheet(s). Using a round cookie cutter create a template by drawing 1 ½-inch circles, about 1-inch apart, on one side of the parchment. Turn the paper over so the circles are on the bottom. Repeat with the second sheet of parchment. Set aside.
• Fit a large pastry bag with a large open decorator tip and set aside.

To prepare the cookie dough:

• In a small food processor, combine half the sugar and the finely grated zest of two lemons. Process until the sugar is light yellow in color and the zest almost disappears.
• In a large mixing bowl combine the cream cheese, butter, lemon infused sugar, the remainder of the granulated sugar, egg yolk, lemon juice, salt and vanilla. Beat on medium-high until the mixture is fluffy, about 3-4 minutes. Scrape down the sides and bottom of the bowl and blend again. Add the flour in 3 additions, scraping down the sides and bottom as needed.

To pipe the cookies:

• Scoop half the cookie dough into the prepared pastry bag. The dough must be very soft to pipe correctly. If needed, place the pastry bag filled with dough in a warm location to soften. You can also rinse your hands under very warm water, then hold the pastry bag for a minute or two to soften.
• Squeeze out generous 1 ½-inch rounds using the template as a guide. The cookies should be similar in size so they match when sandwiched together.

Piping Tips:

• To get the best shape, hold the bag straight up and down with the edge of the tip hovering slightly above the baking sheet. Squeeze the bag firmly until the cookie is almost as wide as the circle. Stop squeezing, pull up and away. If using the Wilton 8B tip, gently press the center of the cookie to smooth using a finger or the back of a small measuring spoon.
• This cookie dough is very forgiving. If you don’t like the way the cookie looks once piped, put the dough back in the bag and try again.
• Bake the cookies until the edges just begin to brown, about 7 to 11 minutes, depending on the size and thickness of the cookie. NOTE: The cookies go from done to too brown in flash so watch the baking time carefully. Transfer the cookies to a rack and cool completely before filling.

To prepare the filling:

• Beat all the filling ingredients until smooth. Scoop the filling into a pastry bag. Cut a small opening at the tip. Match up all the cookies into pairs. Pipe the lemon filling into a swirl covering the whole bottom half of half the cookies. You should use about 1 teaspoon of filling per sandwich cookie. Top with matching cookie to create a sandwich.
• Refrigerate or freeze until needed. Remove from the refrigerator 30 minutes before serving for best flavor and texture.