1. Preheat oven to 350°F (175°C). Line baking sheets with parchment paper.
2. Whisk together flour and salt in a bowl.
3. Cream butter and sugar until fluffy. Add egg yolk and vanilla extract, mix until combined.
4. Gradually add flour mixture, mixing until smooth dough forms.
5. Wrap dough in plastic wrap, chill for at least 30 minutes.
6. Roll dough to 1/8 inch thick on a floured surface. Cut shapes with a cookie cutter.
7. Cut centers out of half using a smaller cutter.
8. Bake 10-12 minutes until edges are golden. Cool completely.
9. Spread jam on bottom cookies, top with cut-out cookies.
10. Dust with powdered sugar before serving.