Preheat your oven to 180 C (350 F) and line a baking sheet with parchment paper.
In a mixing bowl, cream together the softened butter and granulated sugar until light and fluffy.
Add the egg yolks and vanilla extract to the butter-sugar mixture, and beat until well combined.
In a separate bowl, whisk together the all-purpose flour and salt.
Gradually add the dry ingredients to the butter mixture, mixing until a soft dough forms.
Roll the dough into small balls, approximately 1 inch in diameter.
Place the dough balls onto the prepared baking sheet, spacing them about 2 inches apart.
Use your thumb or the back of a teaspoon to make an indentation in the center of each cookie.
Fill each indentation with a small spoonful of raspberry jam, ensuring not to overfill.
Bake the cookies in the preheated oven for 12-15 minutes or until the edges are lightly golden.
Remove the cookies from the oven and allow them to cool on the baking sheet for a few minutes before transferring them to a wire rack to cool completely.
Optional: Dust the cooled cookies with powdered sugar for an added touch of sweetness.
Store the Raspberry Thumbprint Cookies in an airtight container at room temperature.
