• In a large bowl, beat the softened butter and granulated sugar together for 2-3 minutes until creamy.
• Add the egg yolks to the mixture and beat for a few more minutes until well combined.
• Gradually add the all-purpose flour into the mixture. Mix or knead by hand until the dough becomes smooth.
• Split the dough into two equal portions. In one portion, add extra flour and knead until it's fully mixed. In the other half, incorporate cocoa powder until it's well combined.
• Wrap both portions of dough separately in plastic wrap. Refrigerate them for at least 2 hours to firm up.
• Preheat the oven to 350F/176C and line 2 cookie sheets with parchment paper.
• After chilling, roll out each dough portion to the desired thickness. Use cookie cutters to cut the dough into various shapes.
• Bake the cookies for 10-12 minutes. Once the cookies are baked, allow them to cool completely before decorating.

To decorate the cookies

• Melt the white and dark chocolate chips separately using a microwave or a double boiler. Be careful not to overheat them; stir occasionally until smooth.
• Use a spoon or a piping bag to drizzle or dip the cookies into the melted chocolate. Apply chopped nuts and sprinkles.
• For the sandwich cookies, Spread a dollop of jam on the flat side of one cookie in each pair.Gently press another cookie (flat side down) onto the jam-covered side, creating a sandwich.