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