Preheat oven to 350°F (175°C) and line two large baking sheets with parchment paper.

In a stand mixer or large bowl, cream together the softened butter and granulated sugar until the mixture is light and fluffy, approximately 3 minutes.

Add the egg yolk and vanilla extract, beating until fully incorporated.

On low speed, gradually add the flour and salt, mixing until a cohesive dough forms.

Set aside 1/2 cup of the dough to be used for the crumble topping.

Scoop the remaining dough into 1-inch balls (about 1 tablespoon each) and place them 2 inches apart on the prepared baking sheets.

Using a thumb or the back of a small spoon, create a deep indentation in the center of each dough ball.

Fill each indentation with approximately 1/2 teaspoon of raspberry jam.

Take the reserved 1/2 cup of dough and pinch off small pieces, sprinkling them over the jam centers to create a crumble effect.

Bake for 13 to 15 minutes, or until the edges are set and very lightly golden.

Remove from the oven and allow the cookies to cool on the baking sheet for 10 minutes to firm up.

Transfer to a wire rack to cool completely, then dust lightly with powdered sugar before serving.