Part 1: Making the Cookie Dough

1. Combine Dry Ingredients: In a medium-sized bowl, whisk together the all-purpose flour, baking soda, baking powder, and salt. Whisking helps to aerate the flour and evenly distribute the leavening agents, which is crucial for a uniform rise. Set this bowl aside.
2. Cream Butter, Cream Cheese, and Sugar: In the bowl of a stand mixer fitted with the paddle attachment, or in a large bowl with a hand mixer, beat the softened unsalted butter and softened cream cheese on medium speed until smooth and creamy. This should take about 1-2 minutes. Scrape down the sides of the bowl. Add the granulated sugar and beat on medium-high speed for another 3-4 minutes until the mixture is light, pale, and fluffy. This process, known as creaming, incorporates air into the dough, which is the foundation for a soft cookie texture.
3. Add Wet Ingredients: Add the room temperature egg, vanilla extract, fresh lemon zest, and fresh lemon juice to the creamed butter mixture. Beat on medium speed until everything is well combined, about 1 minute. The mixture might look slightly curdled at this point due to the acid in the lemon juice reacting with the fats; this is completely normal. Scrape down the sides and bottom of the bowl again to ensure everything is incorporated.
4. Combine Wet and Dry Ingredients: Reduce the mixer speed to low and gradually add the dry flour mixture to the wet ingredients in three additions. Mix until just combined, being careful not to overmix. Overmixing develops the gluten in the flour, which can result in tough, dense cookies instead of soft and tender ones. Stop mixing as soon as the last streaks of flour have disappeared.
5. Chill the Dough: This is a non-negotiable step! Cover the bowl tightly with plastic wrap and refrigerate the dough for at least 2 hours, and up to 48 hours. Chilling solidifies the fat, which prevents the cookies from spreading into thin, crispy puddles in the oven. It also allows the flour to fully hydrate and the flavors to meld and deepen, resulting in a much more flavorful cookie.

Part 2: Baking the Cookies

1. Preheat and Prepare: When you’re ready to bake, preheat your oven to 350°F (175°C). Line two large baking sheets with parchment paper or silicone baking mats. This prevents sticking and promotes even browning on the bottom of the cookies.
2. Portion the Dough: Remove the chilled dough from the refrigerator. Using a medium cookie scoop (about 1.5 tablespoons), portion the dough into uniform balls. Roll each ball between your palms to make it smooth.
3. Optional Sugar Coating: For a classic sugar cookie crunch and sparkle, you can roll the dough balls in a small bowl of granulated sugar before placing them on the baking sheet. This step is optional but highly recommended for extra texture and a beautiful finish.
4. Arrange and Bake: Place the dough balls about 2 inches apart on the prepared baking sheets to allow for spreading. You can gently press down on the top of each ball with the bottom of a glass to slightly flatten them, but they will spread naturally on their own.
5. Bake to Perfection: Bake for 10-12 minutes, or until the edges are lightly golden brown and the centers are set but still look slightly soft. They will continue to cook on the hot baking sheet after you remove them from the oven. For a chewier cookie, err on the side of underbaking.
6. Cool Completely: Let the cookies cool on the baking sheet for 5 minutes before transferring them to a wire rack to cool completely. It’s crucial that the cookies are at room temperature before you add the glaze, otherwise, the glaze will melt and run right off.

Part 3: Glazing the Cookies

1. Mix the Glaze: In a small bowl, whisk together the sifted powdered sugar, 3 tablespoons of lemon juice, optional lemon zest, and a pinch of salt. The salt helps to balance the sweetness.
2. Adjust Consistency: Whisk until the glaze is smooth and free of lumps. If it’s too thick, add more lemon juice, ½ teaspoon at a time. If it’s too thin, add more sifted powdered sugar, 1 tablespoon at a time. The ideal consistency is thick enough to coat the back of a spoon but still pourable.
3. Glaze the Cookies: Once the cookies are completely cool, you can apply the glaze. You can either dip the top of each cookie directly into the glaze bowl or use a spoon to drizzle the glaze over the cookies on the wire rack. Place a piece of parchment paper under the rack to catch any drips for easy cleanup.
4. Let the Glaze Set: Allow the glaze to set and harden, which can take anywhere from 30 minutes to an hour at room temperature. Once the glaze is firm to the touch, the cookies are ready to be served or stored.