• Preheat oven to 350℉.
• Chop ½ cup of the chocolate chips into small pieces (set the other ½ cup of unchopped chocolate chips aside). Set aside.
• In a small microwave-safe bowl, melt the unsalted butter (½ cup, i.e., 1 stick) for 20-30 seconds until JUST melted.
• Add in granulated sugar (¼ cup) and light brown sugar (½ cup) and use a spatula to stir until combined (do not use a mixer!). Add in egg (1 large) and vanilla extract (1 ½ teaspoons), then mix. Next, add in baking soda (½ teaspoon), baking powder (¼ teaspoon), and salt (¼ teaspoon) and mix again. Add in the gluten-free all-purpose flour (¾ cup) and the almond flour (¾ cup) and mix until all the flour disappears into the dough.
• Lastly, mix in both the ½ cup of chopped chocolate chips and ½ cup of whole chocolate chips.
• Grease a 11.5" metal cookie cake pan (don't have one? See notes section below). If you plan to invert the cake from the pan, you must line the bottom with parchemnt paper and grease the edges of the pan in order for it to release cleanly. Spread dough into a even layer.
• Bake at 350℉ for 12-14 minutes - do NOT overbake or your chocolate chip cookie cake will not be soft. You want the cookie cake to be slightly brown on the top and look slightly underbaked (my oven was perfect at 12 minutes). Remove from oven and place entire pan on a cooling rack. Allow the cookie cake to cool completely before removing. Once cooled, refrigerate the cookie cake for 30-60 minutes. This is essential for a chewy cake that slices cleanly.

  Tip: To remove from pan, use a knife to go around the edges, place a flat platter on top, then flip over the pan to remove. If you used parchment paper, this should come out rather smoothly. After flipping over the cookie cake, flip it over again on the final decorative plate or platter.
• Once fully cooled, using a large star piping tip, pipe around the edges then immediately add sprinkles (the frosting will start hardening quick, so add sprinkles right away!).

To Make Frosting:

• Beat the softened unsalted butter (¼ cup, i.e., ½ stick), vanilla extract (¾ teaspoons), and a pinch of salt on medium-high speed for 1 minute until smooth. Turn the mixer to low speed then add the powdered sugar ¼ cup at a time (1 ¼ cups total). You may need to stop and scrape down sides. One tablespoon at a time, add milk (1-2 tablespoons). Beat on high for 2-3 minutes until creamy and the frosting is at a good consistency to pipe. If it looks too runny, add more powdered sugar. If it looks too stiff, add a tiny bit of milk until you get to the desired consistency.

  This will make just enough frosting to pipe a border along the edges. If you would like more frosting to cover the top or to write words on top, simply double the frosting recipe!