Position a rack in the center of the oven and preheat to 350°. Line 2 baking sheets with either parchment paper or use a Silpat sheet. (If neither are available grease the two baking sheets with unsalted butter.)

Place the almonds in the bowl of a food processor and grind finely. Transfer the almonds to a shallow bowl and set aside.

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

In the bowl of an electric mixer, using the paddle attachment, beat the butter, shortening, and brown sugar at medium speed until light and creamy. Beat in the egg until well blended, scraping down the sides if necessary. Beat in the vanilla extract. At low speed incorporate the oats until well blended. Let it rest for 15 to 30 minutes if time permitting.

Pinch off pieces of the dough and shape into 1-inch balls. Roll one of the balls in the ground almond, coating completely. Place the ball on the cookie sheet and flatten it slightly with the palm of your hand. Press your thumb into the center of the cookie to form an indentation. (if pressed to hard and the cookie lose his round shape, push the edges back together to have it all round)

Spoon about ½ teaspoon of the forest berries jam into the indentation filling it. Repeat with the remaining dough balls arranging them 1 ½ inch apart on the baking sheet.

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

Dust the cookies with sifted powder sugar before serving.