01 - Preheat oven to 350°F. Line two baking sheets with parchment paper.
02 - In a large bowl, beat softened butter and granulated sugar until light and fluffy.
03 - Mix in egg yolk and vanilla extract until fully incorporated.
04 - Add salt and flour, mixing just until combined. Avoid overmixing.
05 - Scoop tablespoon portions of dough, roll into balls, and place on prepared baking sheets 2 inches apart.
06 - Press thumb or back of small spoon into center of each dough ball to form a well.
07 - Spoon approximately 1/2 teaspoon of flower jam into each indentation.
08 - Bake for 12 to 15 minutes until edges are lightly golden.
09 - Let cookies rest on baking sheets for 5 minutes, then transfer to wire rack. Dust with powdered sugar once cooled if desired.