In a small saucepan, whisk together the egg yolks, granulated sugar, and lemon juice. 

Place the saucepan over medium low heat and warm the curd just until you begin to see bubbles around the edges of the pan– about 2 minutes. 

Then reduce the heat to low and cook for 1-2 minutes, whisking constantly, or until the curd has thickened enough to coat the back of a spoon. Make sure to keep an eye on it– we don’t want to scramble the eggs! 

Remove the pan from the heat and add the butter. Whisk to combine. If the curd has any lumps, you can always strain it through a fine mesh sieve to remove them. 

Place the curd into a small bowl and cover it with plastic wrap so that the plastic is touching the surface of the curd– we don’t want it to form a skin. 

Place the curd in the fridge until completely chilled– about 2 hours. 

Line two large baking sheets with parchment paper and set them aside. 

Add the softened butter, powdered sugar, and lemon zest to the bowl of a stand mixer fitted with the paddle attachment. Beat on medium speed until well combined– about 1-2 minutes. 

Next, add the flour and salt. Mix on low speed until a crumbly dough forms. Make sure to scrape down the sides of the bowl as needed. 

Place the cookie dough in the fridge to chill for 20 minutes. While the cookies chill, preheat the oven to 350F. 

When the oven is ready, scoop out 1.5 tablespoon sized portions and roll them into smooth balls. Flatten them into ½” discs and then use your finger (or the back of a spoon) to create a small dent in the center.

Bake the chilled cookies for 13-15 minutes, or just until they are golden brown on the bottoms. The cookies will puff slightly as they bake– if needed, press the centers of the cookies in slightly when they come out of the oven to create a deeper hole.

Allow them to cool completely on the baking sheet and then fill the center of each cookie with 1-2 teaspoons of homemade lemon curd. Dust with powdered sugar if desired.