Step 1: Brine the Lemon (Optional, but Highly Recommended). In a small bowl, combine the dill pickle brine and water. Place the whole lemon in the brine, making sure it’s submerged. Let it sit at room temperature for at least 30 minutes, or refrigerate for up to a few hours. This will infuse the zest with a subtle pickle flavor.

Step 2: Make the Shortbread Dough (Dry Ingredients). In a medium bowl, whisk together the flour and cornstarch.

Step 3: Cream Butter and Sugar. In a stand mixer fitted with the paddle attachment, beat together the softened butter, granulated sugar, and lemon zest (zest the brined lemon after removing it from the brine and drying it) over medium speed until creamy, 3 to 4 minutes.

Step 4: Add Lemon Juice and Vanilla. Scrape the bottoms and sides of the bowl and beat in the lemon juice and vanilla extract.

Step 5: Gradually Add Dry Ingredients. With the mixer on low speed, gradually add the flour mixture to the butter mixture, beating until just combined after each addition. Stir in the dill pickle powder, and optional fresh dill.

Step 6: Chill the Dough. On a lightly floured work surface, place the dough. Divide the dough in half and form into disks. Wrap each disk in plastic wrap and refrigerate until firm, 30 minutes to 1 hour.

Step 7: Preheat Oven and Prepare Baking Sheets. Place one oven rack in the upper third of the oven and a second oven rack in the lower third of the oven. Preheat the oven to 375°F (190°C). Line two baking sheets with parchment paper.

Step 8: Roll and Cut Dough. Working with one disk of dough at a time and keeping the second disk refrigerated, lightly flour a work surface. Roll the dough out to ¼-inch thick.

Step 9: Stamp and Cut (Optional). If using a cookie stamp, press a floured cookie stamp into the dough to make an impression.

Step 10: Cut into Circles. Use a 2- to 3-inch cookie cutter to cut the dough into circles.

Step 11: Transfer to Baking Sheets. Using a thin spatula, transfer the cookies to the prepared baking sheets, spacing them about 2 inches apart. Refrigerate the scraps.

Step 12: Bake. Bake until the tops are dry and the bottoms begin to turn golden, 9 to 10 minutes.

Step 13: Cool. Let cool for about 5 minutes on the pan, then transfer the cookies to a cooling rack to cool completely. Repeat with the remaining dough and scraps, rerolling only once for smooth cookies.

Step 14: Make the Glaze. While the cookies are cooling, make the glaze. In a medium bowl, combine the powdered sugar, melted butter, and 1 tablespoon of lemon juice.

Step 15: Adjust Glaze Consistency. Add the remaining lemon juice, 1 teaspoon at a time, until the icing falls off the whisk in a fluid stream and the fallen ribbon of icing holds its shape for only a few seconds before sinking back into the bowl of icing. If the glaze is still too thick, add water, 1 teaspoon at a time.

Step 16: Glaze the Cookies. Working with one cookie at a time, use a pastry brush to brush a thin layer of glaze onto each cooled cookie. If the pastry brush is leaving behind too many streaks or the glaze feels too thick, whisk in another teaspoon of water.

Step 17: Let Glaze Set. Allow the glazed cookies to set for 15 minutes.

Step 18: Serve. Store at room temperature in an airtight container for up to 1 week. Serve with dill pickle relish on the side, if desired.