Preheat the oven to 350°F and line two baking sheets with parchment paper.

Add the softened butter and powdered sugar to a large mixing bowl and beat until smooth and creamy.

Add the egg yolk and vanilla extract and mix until fully combined.

Add the salt and gradually mix in the flour until a soft dough forms.

Scoop the dough and roll it into 1-inch balls using your hands.

Place the dough balls on the prepared baking sheets, leaving about two inches between each one.

Press your thumb gently into the center of each dough ball to create a shallow indentation.

Stir the raspberry jam until smooth.

Spoon about half a teaspoon of jam into the center of each cookie.

Bake for 12 to 14 minutes until the edges are set and the bottoms are lightly golden.

Remove the cookies from the oven and allow them to cool on the baking sheet for five minutes.

Transfer the cookies to a wire rack and allow them to cool completely before serving or storing.