Preheat the oven to 350°F (175°C). Line baking sheets with parchment paper.
In a large mixing bowl, cream together the softened butter and granulated sugar until light and fluffy using an electric mixer.
Beat in the egg yolk, vanilla extract, and ground cardamom (if using) until well combined.
Gradually mix in the all-purpose flour and salt on low speed until a soft dough forms.
Divide the dough into two equal portions, shape into flat disks, wrap in plastic wrap, and refrigerate for at least 1 hour.
Once chilled, roll out the dough on a lightly floured surface to about 1/4-inch thickness. Use cookie cutters to create festive shapes, or roll into small balls for thumbprint cookies.
For thumbprint cookies, press your thumb gently into the center of each ball and fill the indentation with a small dollop of raspberry jam or another fruit preserve.
Place the shaped cookies on the prepared baking sheets, spacing them about 1 inch apart.
Bake for 10–12 minutes, or until the edges are lightly golden. Avoid overbaking to keep the cookies soft.
Let the cookies cool on the baking sheet for 5 minutes, then transfer them to a wire rack to cool completely.
Once cooled, dust the cookies with powdered sugar or decorate with sliced almonds as desired.