• Take the butter out of the fridge so it softens a bit.
• In a large bowl, mix flour, salt and sugar. Make a mould.
• Add butter, egg and egg yolks to the mould.
• Knead the dough for few minutes until all ingredients combine.
• Make a ball out of the dough and wrap cling film around it. Store the dough in the fridge for at least 1 hour.
• Divide the dough into four equal parts and store the ones you won't use in the fridge. If the dough gets too soft, the raw cookies will not keep their shape.
• Prepare two baking sheets with parchment paper.
• Preheat the oven to 180°C (350°F).
• Sprinkle flour on the worktop.
• Roll the dough to about 4-5mm thickness (1/5 inch).
• Using a cookie cutter, cut the dough into egg-shaped pieces (half of them should have a hole in them). Re-roll the remaining dough and continue cutting until all is used.
• Repeat until you run out of dough. 
• Arrange cookies on the parchment paper of the baking sheet (2-3cm apart - 1 inch)
• Bake for 8-10 minutes.
• Let them cool on the baking sheet for a few minutes before transferring them to a cooling rack.

Filling

• Preheat the jam slightly on a medium heat.
• Spread 1/2-1 teaspoon of jam evenly on each dish without a hole.
• Immediately cover the bottom cookie and jam with the top cookie with a hole.
• Sprinkle with powdered sugar.
• Store cookies in an airtight container for up to 4 weeks.