Preheat your oven to 350°F (175°C) and line a baking sheet with parchment paper.

In a large mixing bowl, cream the softened butter and granulated sugar until light and fluffy.

Add the egg yolk and vanilla extract, mixing well.

Gradually incorporate the flour and salt into the butter mixture until forming a smooth dough.

Roll the dough into balls about 1 inch in diameter and arrange them on the baking sheet.

With your thumb, create an indentation in the center of each ball for the jam.

Spoon a small amount of fruit jam into each indentation.

Bake in the preheated oven for 12-15 minutes until the edges are lightly golden.

Let the cookies cool on the baking sheet for a few minutes before transferring them to a wire rack to cool completely.

Optionally, add edible flowers for decoration before serving.