Preheat oven to 350 F. Lightly grease two baking sheets with butter. Place the almonds in a food processor bowl and process for about 15 seconds until finely ground. Transfer the ground almonds to a shallow bowl and set aside.

In a medium bowl, whisk together the oats, flour and salt. Set aside.

In a large bowl, cream the butter and brown sugar together until light and creamy. With an electric mixer, beat in the egg yolk until well blended. Beat in the almond and vanilla extracts. At low speed, add the oat mixture, mixing just until blended.

Roll small pieces of dough into 1-in balls. Roll one of the balls in the ground almonds, coating it completely.

Place the ball on a greased baking sheet and flatten it slightly with your palm, then press your thumb into the center of the cookie to form an indentation.

Spoon about ½ teaspoon of the raspberry jam into the thumbprint, filling it. Repeat with the remaining dough balls, arranging them 1 ½ inches apart on the baking sheet.

Bake the cookies one sheet at a time for 14 to 16 minutes until golden brown. Transfer the cookies to a wire rack and cool completely.