Preparation

• Preheat oven to 350°F. Line two baking sheets with parchment paper.
  Combine the flour, cornstarch, baking powder, salt, butter, sugar, egg and vanilla extract in the bowl of a food processor. Mix for a minute to form a ball. Transfer to a work surface to gather all the dough. Place in a covered bowl and refrigerate 30 minutes.
  (You may also use a stand mixer fitted with the paddle attachment to accomplish the same results).
  Divide the chilled dough into 20 equal pieces. Shape into balls. Make an indentation in each ball and spoon about 1 teaspoon of Nutella or chocolate bits inside. Close the dough over the filling, making sure dough is covering the filling on all sides, and pinch the top to seal the cookie. Roll to shape evenly into round or oval shapes.
  Place cookies on cookie sheet. Bake for 18-20 minutes. Let cool on the pans. Brush cookies with jam and sprinkle with coconut.