1. Make the Dough
In a medium bowl, I whisk together the flour, cornstarch, and salt until they’re best friends. Set that aside. In a large bowl, I cream the butter and sugar with my mixer until it’s fluffy and pale about 1 minute. Then, I add the lemon zest, lemon juice, egg, and vanilla. At first, it’ll look a little curdled (don’t panic!), but once I mix in the dry ingredients, it smooths out beautifully.

2. Chill the Dough
This dough is soft, so I cover the bowl and refrigerate it for at least 3 hours (or up to 3 days). Chilling firms it up, making it easier to shape later.

3. Shape & Sugar-Coated Magic
After chilling, I line baking sheets with parchment. I scoop cold dough into 1-tablespoon balls, roll each in granulated sugar, and place them 2 inches apart. Then, I press my thumb (or the back of a teaspoon) into the center of each to make a little well.

4. Fill ‘Em Up
I spoon ½ teaspoon of lemon curd into each indentation. Pro tip: Don’t overfill the curd bubbles a bit while baking.

5. Bake to Perfection
I preheat the oven to 350°F (177°C) and pop the baking sheets back in the fridge while it heats. Cold dough = less spreading! Bake for 12–13 minutes until the edges are just golden. Let them cool on the sheet for 5 minutes, then transfer to a rack.

6. Drizzle the Icing
Once cool, I whisk the confectioners’ sugar and lemon juice into a thin glaze. Drizzle it over the cookies with a fork or squeeze bottle. Let it set for 30 minutes then dig in!