Step 1

Preheat oven to 350°F. Prepare the Dough: Cream softened butter and brown sugar in a medium bowl with an electric hand mixer until light and fluffy. Mix in egg yolks and vanilla. Gradually add flour and salt, stirring until combined. Wrap the dough in plastic wrap and refrigerate for 30 minutes until chilled.

Step 2

Shape the Cookies: Roll chilled dough into 1-inch balls and place them on the ungreased baking sheet. Press a thumb or the back of a 1/4 teaspoon into each ball to create an indentation.

Step 3

Fill and Bake: Add a 1/4 teaspoon of jam to each indentation. Bake for 12–15 minutes, or until edges are golden brown.

Step 4

Cool: Allow cookies to cool for 5 minutes on the baking sheet, then transfer to a wire rack to cool completely. Decorate with drizzled white chocolate if desired.