1. Preheat oven to 350 degrees F. Line 2 baking sheet with parchment paper and set aside.
2. In the bowl of your stand mixed fixed with paddle attachment, cream shortening, butter and sugar. Add eggs one at a time, mixing well between each addition. Add vanilla and mix well.
3. Finally, add the dry ingredients and beat until a soft, sticky dough comes together. Let the dough rest in the refrigerator for about 20 minutes.
4. Prepare a pastry bag fitted with a star-shaped tip and fill with the cookie dough. Pipe your cookies about 2-inches long and 1-inch apart. Bake for 10-12 minutes or until the edges are lightly golden.
5. Remove and let cool on a wire rack.

Assembly:

1. Prepare your assembly by lining two baking sheets with wax paper and pour rainbow sprinkles in a shallow dish or bowl. Alternatively if you like you can also dip your cookies in chocolate sprinkles, chopped nuts like pistachios or almonds. I chose to stick to the traditional rainbow sprinkles, reminiscent to those you find at the Italian bakery.
2. In a double-boiler, melt down dark chocolate chips with 3 tablespoons heavy cream. Stir until the chocolate has melted down completely and is smooth.
3. Spread desired jam on one cookie (about ½ teaspoon), sandwich with another cookie then dip in the chocolate and then the rainbow sprinkles. You should get about 2 dozen cookies out of this. For the finishing touch, sprinkle with confectioner's sugar.
4. Serve and enjoy!