In a large mixing bowl, cream together butter and sugar.
Beat in egg yolks, vanilla, and almond extract.
Beat in flour and salt until just combined.
Refrigerate for 1 hour or until dough is easy to handle.
Shape into 1-inch balls.
Roll each ball in chopped almonds to thoroughly coat.
Arrange balls two inches apart on parchment paper or silicone mat-lined baking sheets.
Press an indentation in the center of each dough ball using your thumb or the end of a wooden spoon.
Bake at 375 degrees for 10-12 minutes, or until cookies appear set and edges are lightly browned.
Remove to wire racks to cool completely.
In a small microwave-safe bowl, heat the jam for 30 seconds, or until thin and liquidy.
Spoon about a teaspoonful of jam into the center of each thumbprint.
Drizzle melted white chocolate over thumbprints.
Allow to set. Store in airtight containers.