Preparation:

1. Step 1: Preheat the oven to 350°F (177°C).
2. Step 2: Cut two pieces of parchment paper to fit your baking sheets. Draw 1 ½-inch circles, approximately 1-inch apart, on one side of each parchment piece. Flip the parchment so the drawn circles are on the underside. Set aside.
3. Step 3: Prepare a large pastry bag by fitting it with a large open decorator tip.

Cookie Dough:

1. Step 1: In a small food processor, combine half of the granulated sugar with the finely grated zest of two lemons. Process until the sugar adopts a light yellow hue and the zest is well integrated.
2. Step 2: In a sizable mixing bowl, blend the cream cheese, butter, lemon-infused sugar, the remaining granulated sugar, egg yolk, lemon juice, salt, and vanilla extract. Beat on medium-high speed until the mixture achieves a fluffy consistency, approximately 3-4 minutes. Periodically scrape down the sides and bottom of the bowl, then continue to mix. Incorporate the flour in three separate additions, scraping the sides and bottom of the bowl as necessary.

Piping the Cookies:

1. Step 1: Transfer half of the cookie dough into the prepared pastry bag. The dough should be exceptionally soft for optimal piping. If necessary, warm the dough by placing the pastry bag in a warm location or by holding it with hands rinsed in warm water.
2. Step 2: Pipe out generous 1 ½-inch rounds onto the parchment paper, using the pre-drawn circles as a guide. Ensure the cookies are uniform in size for consistent baking and assembly.