Preparation

1. Allow butter to come to room temperature.
2. Sift flour into a small bowl or pour into bowl and whisk it.
3. Make two small makeshift pastry bags by rolling a piece of wax paper into a tight cone and taping it closed; these will be used to pipe the chocolate onto the cookies. Leave the point of the cone closed; you’ll cut it open once filled.
4. Preheat oven to 180°C (350°F).

Directions

1. Make cookies.
   
   1. In a large bowl whip butter until fluffy.
   2. Add egg yolks and sugar and whip until pale and fluffy.
   3. Add flour and fold with a spatula until mixed; don’t stir it, or the cookies will come out tough.
   4. Divide into three chunks to make it easier to work with; place each on a piece of plastic wrap, cover with another piece of plastic wrap, and roll out into a sheet about 3mm (one-eighth-inch) thick.
   5. Chill sheets in refrigerator for 30 minutes to an hour.
   6. Remove from refrigerator and use a cookie-cutter to cut into desired shape; leave half of them solid, and use a smaller cookie cutter to punch a hole into the middle of the other half. Ball, roll, and chill trimmings and holes to make remainder of cookies.
   7. Bake chilled cookies on cookie sheet for 10-15 minutes, until just slightly golden. If the dough is too warm when the cookies go into the oven, they will spread out too much and the top and bottom halves may not match, so make sure they’re cold before baking.
   8. Cool on wire rack while preparing filling.
2. Make buttercream filling.
   
   1. In a small bowl cream the butter with an electric mixer.
   2. Add 180g (1⅔ cups) of powdered sugar and mix until smooth.
   3. Add vanilla and stir until well mixed.
   4. Check the consistency; if it is too soft, add more sugar and mix thoroughly.
3. Assemble and decorate cookies.
   
   1. Microwave jam until soft enough to spread.
   2. Take a solid cookie, spread a generous layer of buttercream on it, then a thin layer of jam, and gently press a cookie just enough to stick together; careful, they’re easy to crack if you push too hard.
   3. Microwave the semi-sweet chocolate until liquid, pour it into one of the makeshift pastry bags, twist the open end closed, and cut a bit off the end to make a small hole. Pipe the chocolate in a zigzag pattern across each cookie.
   4. Repeat with the white chocolate.