Preheat your oven to 350°F (175°C) and line a baking sheet with parchment paper.
In a bowl, cream together the softened butter and powdered sugar until light and fluffy.
Add the egg yolk, vanilla extract, and almond extract, mixing until fully combined.
In another bowl, whisk together the all-purpose flour, almond flour, and salt. Gradually add this dry mixture to the butter mixture, blending until a soft dough forms.
Scoop tablespoons of dough and roll them into balls, placing them about 2 inches apart on the prepared baking sheet.
Using your thumb or the back of a spoon, make a small indentation in the center of each dough ball.
Fill each indentation with raspberry jam, ensuring not to overfill.
Press a few sliced almonds around the edge of each thumbprint for added crunch and decoration.
Bake for 12-15 minutes, or until the edges start to turn golden. Remove from the oven and let cool on the baking sheet for a few minutes before transferring to a wire rack to cool completely.