1. To make the ganache, put the white chocolate chips in a medium sized bowl.
2. Put the amaretto and heavy whipping cream in a microwave safe measuring cup or bowl and microwave until it begins to boil.
3. Pour the cream over the white chocolate chips and allow to sit for 2-3 minutes, then whisk until smooth. If needed, microwave the mixture for 10-20 more seconds, then whisk until smooth.
4. Set the ganache in the fridge to firm up, about 2-3 hours.
5. To make the cupcakes, preheat oven to 350°F (176°C) and prepare a cupcake pan with cupcake liners.
6. In a large mixing bowl, cream butter and sugar together until light in color and fluffy, about 3-4 minutes. Do not skimp on the amount of creaming time.
7. Add sour cream and almond extract and mix until well combined.
8. Add egg whites in two batches, mixing until well combined after each. Scrape down the sides of the bowl as needed to be sure all ingredients are well incorporated.
9. Combine dry ingredients in a separate bowl, then combine the milk and water in a small measuring cup.
10. Add half of the dry ingredients to the batter and mix until well combined. Add the milk mixture and mix until well combined. Add remaining dry ingredients and mix until well combined. Scrape down the sides of the bowl as needed to be sure all ingredients are well incorporated.
11. Fill the cupcake liners about halfway. Bake for 15-17 minutes, or until a toothpick inserted comes out with a few crumbs.
12. Remove cupcakes from oven and allow to cool for 2-3 minutes, then remove to cooling rack to finish cooling.
13. While the cupcakes cool, finish the ganache. Put the ganache in the bowl of a mixer and whip with the whisk attachment until soft peaks form, about 5-7 minutes. You’ll notice the ganache lighten in color.
14. Cut out the centers of the cupcakes. You can use a cupcake corer or a knife.
15. Fill the centers of the cupcakes with the white chocolate ganache. Set the cupcakes in the fridge while you make the frosting.
16. To make the frosting, combine the butter and shortening with a mixer until smooth.
17. Add about half of the powdered sugar and mix until smooth and well combined.
18. Add 3 tablespoons of water or milk and the almond extract to the frosting and mix until well combined.
19. Add remaining powdered sugar and mix until smooth. Add additional water or milk as needed to get the right consistency.
20. Pipe the frosting onto the cupcakes. I used Ateco tip 844.
21. Press broken sliced almonds onto the sides of the bottom of the frosting. Refrigerate cupcakes until ready to serve. Serve at room temperature.