Step 1

Hard boil 3 of the eggs, then remove the yolk. Using a spoon, press the egg yolks through a fine-mesh sieve, until it turns into a paste. The finer the sieve is, the better. Using a fork, xix together with the raw egg yolks to create a paste.

Step 2

Mix together butter, sugar, lemon zest, and your egg yolk paste until incorporated. Add in the flour and milk and knead until you have a cohesive, smooth dough.

Step 3

Cover the dough and transfer to the fridge to chill for 60 minutes. In the meantime, preheat oven to 390° Fahrenheit (200° Celsius).

Step 4

On a surface dusted in flour, roll out the dough to 1/10 inch (3 mm) thickness, and cut out your favorite shapes, cutting out the middle for half of them, so you see the jam through it after assembly. Note: You can use a special cookie cutter for these, or you can create your own Spitzbuben by creating any kinds of peek-a-boo holes in the top cookie. If they are larger sized cookie shapes like mine, you'll end up with less than 40 cookies.

Step 5

Transfer cookies to baking sheets covered in parchment paper or fitted with baking mats and bake for 8 to 10 minutes on the middle rack until just starting to turn golden around the edges. Note about baking: My last batch could fit on just one baking sheet instead of two, and the cookies baked much faster. I would also recommend baking the top pieces with cut-outs separately from the bottom pieces as they tend to bake just a minute or so faster.

Step 6

After baking, carefully pull the baking sheet or parchment paper onto a cooling rack, allowing the cookies to harden and cool down faster. Dust top cookie with powdered sugar. Using spoons, put about 1/2 teaspoon of jam on each bottom cookie (you can warm it up in the microwave for a few seconds to help it spread out better), then assemble the cookies by placing the sugar-dusted top cookie on the jam-covered bottom cookie. These keep well in a cookie jar for up to 2 months (but no way you'll have any left after the first week).