Preheat your oven to 350 degrees F. Line three baking sheets with parchment paper. Set aside.
In a medium mixing bowl, stir together the flour, baking powder, and salt. Set aside.
In the bowl of a stand mixer with the paddle attachment, beat the butter and sugar together for 3 minutes until light and fluffy. (You can use a large mixing bowl with a hand mixer instead of a stand mixer.)
Add the eggs and egg yolks to the butter mixture one at a time, mixing after each addition. Then add the cake batter extract, almond extract, and vanilla extract, mix until combined
Add 1/3 of the flour mixture to the wet ingredients and mix until just combined. Repeat with the remaining dry ingredients. Don't forget to scrape down the sides of the bowl as needed.
Portion the cookie dough into 12 equal portions, just over 4 ounces each. Roll each portion into a smooth ball and place them on the baking sheet 6 inches apart. The cookies will spread quite a bit, so you will have to bake in batches. (I put 4 cookies on each baking sheet to be safe.)
Gently press down on the cookie dough balls and flatten them out into a large flat circle.
Bake for 13-15 minutes until lightly golden brown and the cookies appear dry in the center. Remove from the oven and bake the next tray of cookies. Let the cookies cool completely on the baking sheet.
While the cookies are cooling, make the frosting by placing the chopped chocolate into a large heat-proof bowl.
Add the heavy cream and corn syrup to a small saucepan and place over medium heat, stirring occasionally. As soon as it starts to simmer, pour the cream mixture over the chocolate. Let that sit for 5 minutes. Then whisk the chocolate until smooth, it will take a while to come together fully.
Let the ganache cool to room temperature until firm but able to be piped onto the cookies. (This will take a while so I suggest whisking it every few minutes to help cool it down faster.) To speed up the process even more you can place the bowl in the fridge and whisk it again every few minutes. Just be sure the frosting doesn't become so cold and hard that it's no longer pipeable.
Place the ganache into a pastry bag with an open star tip. Pipe large rosettes on top of each cookie, but do not go all the way to the edge. You want to be able to see some of the cookies along the outside. Add the chocolate sprinkles and serve immediately or serve with the frosting only.
Notes
I add corn syrup to the ganache to keep it glossy, if you don’t have or don’t want to use corn syrup just sub another ¼ cup of heavy cream.
Keeps at room temperature in an airtight container for up to 3 days. Keep in the fridge for up to 5 days. Freeze for up to 3 months. Best enjoyed at room temperature.