Preheat oven to 350 degrees. Line two baking sheets with parchment paper, set aside.
To make the lemon curd, in a large microwaveable bowl, combine sugar, butter, lemon juice, lemon zest and vanilla bean paste. Whisk in egg, then egg yolk. Place in the mixture into the microwave and cook for 1 minute at a time, whisking after each minute. You will need to do a total of 4-6 minutes or until the curd coats the back of a spatula (it will look jelly-like). The time will depend on the strength of your microwave.
Pour the hot curd through a mesh sieve to remove any “eggy” parts. Store in an air-tight container in the refrigerator until cookies have completely cooled.
o make the cookies, in the bowl of a stand mixer, beat together butter, sugar, lemon juice, lemon zest and vanilla until light and fluffy, scraping down the sides of the bowl if necessary. Add egg yolks one at a time and mix just until incorporated. Add salt, then with mixing speed on low, gradually add flour a ½ cup at a time. Mix until incorporated.
Roll dough into 1″ balls, place on prepared baking sheets. Lightly pat down to flatten (just a little bit), then using your thumb press little wells into each. Place into the oven and bake for 13-15 minutes or until the edges turn golden brown in color. Remove from the oven and allow to cool on sheets for 5 minutes before transferring to a wire rack to cool completely. Once cookies have cooled (30 minutes or so) using a mesh sieve, gently dust powdered sugar over each cookie. Place a dollop of chilled lemon curd in the center of each, then place in refrigerator to set up. Serve & enjoy!