Prepare the Cookie Dough. Cream together butter and sugar until light and fluffy. Add egg yolk and vanilla extract, then gradually mix in the flour and salt until the dough forms.
Chill the Dough. Wrap the cookie dough in plastic wrap and refrigerate it for about 30 minutes.
Shape and Fill. Roll the dough into small balls and place them on a baking sheet. Make an indentation in each cookie with your thumb or the back of a measuring spoon. Fill each indentation with raspberry jam.
Bake to Perfection. Bake the cookies in a preheated oven until they're golden brown around the edges.
Cool and Enjoy. Allow the cookies to cool on a wire rack. Once cooled, dust them with powdered sugar for an extra touch of sweetness.