Lemony Linzer cookies with homemade lemon curd

Separate four eggs and put the yolks in a big heat-proof bowl.

Zest two lemons into the bowl, then juice them plus one more for half a cup of juice; cut the stick of butter into chunks.

Add the granulated sugar and whisk; set the bowl over a pot a third full of water brought to a boil and dropped to a simmer.

Whisk constantly for 10 minutes until it thickens, or to 170F / 77C on a thermometer.

Off the heat whisk in the butter until fully melted; it thickens more as it cools. Store in jars in the refrigerator up to a week, or freeze up to three months.

In the mixer with the paddle, combine the soft butter, granulated sugar, powdered sugar, salt and vanilla; beat on low until combined, then high until fluffy, scraping the bowl down.

Add the flour a little at a time on low speed until incorporated.

Roll out on a lightly floured surface to a quarter inch thick and cut out with Linzer cutters; reroll the scraps with as little flour as possible.

Transfer to parchment lined trays and chill 20 to 30 minutes until set; preheat the oven to 350F.

Bake about 20 minutes, until lightly golden on top and golden at the edges; cool completely.

Dust the tops with confectioners sugar; put a teaspoon of lemon curd on each bottom cookie and set the tops on.

Let set in the refrigerator 30 minutes, the freezer 10 to 15 minutes, or at room temperature about an hour so the curd glues them.