Preheat your oven to 350°F and line a baking sheet with parchment paper. While the oven heats, ensure your egg is at room temperature (this helps it emulsify better with the butter), juice your lemon to get 2 tablespoons plus 1 tablespoon for the glaze, and zest the lemon to get 1 1/2 tablespoons. Sift the powdered sugar for the glaze to remove any lumps so it combines smoothly. I always measure my gluten-free flour by spooning it into the measuring cup and leveling it off—this prevents compacting and gives you the right amount every time.

In a medium bowl, beat the softened butter and sugar together for 2-3 minutes until the mixture is pale, fluffy, and noticeably lighter in color. This creaming process incorporates air into the batter, which helps the cookies rise and become tender. Make sure your butter is soft enough to blend easily but not melted.

Add the room-temperature egg, vanilla, 2 tablespoons of fresh lemon juice, and lemon zest to the butter-sugar mixture from Step 2. Mix on medium speed for about 1 minute until everything is well combined and the batter looks smooth and cohesive. The fresh lemon juice and zest will start building the bright flavor at this stage, and the egg acts as a binder for your gluten-free dough.

In a separate small bowl, whisk together the gluten-free flour, baking powder, baking soda, and salt. Add the dry mixture to your wet ingredients from Step 3 and mix on low speed until just combined—the dough should come together without any visible streaks of flour. Don't overmix, as this can make gluten-free cookies tough. Fold in the poppy seeds by hand using a spatula until evenly distributed throughout the dough.

Using a cookie scoop or rounded tablespoon, portion the dough from Step 4 onto your prepared baking sheet, spacing them about 2 inches apart. Bake for 10-12 minutes until the edges are lightly golden but the centers still look slightly underbaked—this is key for tender cookies. I prefer cookies that are just set on top but still have a tiny bit of give in the center, so I err toward the 10-minute mark.

Let the baked cookies cool on the baking sheet for 10 minutes—this allows them to set up enough to move without breaking but stay warm enough for the glaze to adhere. After 10 minutes, transfer them to a wire cooling rack to cool completely before glazing.

While the cookies cool, whisk together the sifted powdered sugar from Step 1, 1 tablespoon of fresh lemon juice, and honey in a small bowl until you have a smooth, drizzleable glaze. Once the cookies are completely cool, drizzle or spread the glaze generously over each cookie. The honey adds just a touch of richness and helps the glaze set nicely without becoming rock-hard. Let the glaze set for a few minutes before serving.