1. Preheat the oven to 350°F (190°C). Prepare a cookie sheet with parchment paper or a silicone baking mat.
2. In a medium sized bowl, combine the flour, cocoa and baking powder. Set aside.
3. Cream the sugar and butter until light and fluffy, 3-4 minutes.
4. Add the egg and milk and mix until combined.
5. Add the flour mixture and mix until well combined.
6. Drop level tablespoons of cookie dough onto a lined cookie sheet. You could also use a piping bag and round tip to pipe the dough.
7. Bake for 6-8 minutes. Allow the cookies to cool on the cookie sheet for 2-3 minutes, then remove to a cooling rack.
8. To make the frosting, beat the butter and shortening until smooth.
9. Add about half of the powdered sugar and mix until well combined.
10. Add 2 tablespoons of strawberry jam and mix until smooth.
11. Add the remaining powdered sugar and mix until smooth.
12. Add an additional 2-3 tablespoons of strawberry jam, then mix until smooth. Add some pink coloring to the frosting, if desired.
13. Create cookie sandwiches with two cookies at a time. Pipe frosting onto one cookie, then add the second. Add sprinkles around the sides of the cookie so that they stick to the frosting.
14. Store cookies in an air tight container. Best for 2-3 days.