Preheat oven to 350 degrees. Prepare baking sheets. In a stand mixer with the paddle attachment cream butter and sugar until light and fluffy, 1-2 minutes.
1
Add in egg yolk and vanilla and mix until combined. Make sure to scrape down the sides of the bowl.
2
Add the salt and flour and mix until combined. It is okay if you mix the dough.
3
Form dough into 1 tablespoon balls and place onto the prepared baking sheet. Using either you thumb or a 1/2 teaspoon press indentations in the center of each cookie.
4
Fill each cookie with 1/2 tsp of your favorite jam or preserves. We did strawberry, blueberry and apricot jam.
5
Place in the oven and bake for 8-10 minutes or until the cookies look set and look slightly golden brown.