Preheat oven to 375 degrees
In a large bowl, whisk flour, baking powder, cornstarch, cream of tartar and salt
In the bowl of a stand mixer, cream butter and sugar until light and fluffy
Beat in the egg, almond, and vanilla extracts until fully combined
Gradually add flour mixture until well blended
Allow batter to set for 10 minutes
Using a medium-sized cookie scoop, drop the cookie dough onto a well-greased baking pan or parchment paper.
Bake in the oven at 375 degrees for 10-12 minutes. You want to remove them from the oven when they feel undercooked. You don't want them to get brown or crisp around the edges.
Place on a wire rack until fully cooled
FUDGE FROSTING
In the bowl of a stand mixer on medium speed, cream butter, and cocoa powder, and espresso powder if using, until well combined.
Place the chocolate chips and coconut oil in a microwave-safe bowl. Heat at 30-second intervals until fully melted, stirring in between eac. Allow the chocolate to cool.
Mix in the melted chocolate chips until fully blended
Add powdered sugar and milk, alternating between each, and mix on high for 1 minute after each addition.
Add about 1 tbsp of frosting to the top of each cookie.