For the macarons:

1. First sift the almond flour, powdered sugar, cocoa powder, and salt back and forth four times between two bowls using a mesh strainer. Alternatively you can also pulse in a food processor 7-8 times. Set aside.
2. Line a baking sheet with parchment. Either print and place the Mickey Mouse template (download link above!) under the parchment OR using the Mickey Mouse cookie cutter, trace six outlines using the cutter as a guide leaving at least an 1″ between shapes. Flip parchment over so that you can still see outlines, but the graphite will not transfer to macarons. Set aside.
3. In the bowl of a stand mixer fitted with the whisk attachment, add in the egg white and whisk on medium-low until slightly foamy, about 30 seconds. Add in the cream of tartar and whisk on medium until soft peaks appear. Then slowly pour in the sugar. Whisk on high until stiff peaks form, about 2-3 minutes.
4. Remove the bowl from the mixer. Sift the entire dry mixture into the egg whites. Fold them until all the dry ingredients are incorporated and no egg whites remain. Egg whites will deflate and mixture should be the consistency of cake batter when they are ready. See notes below.
5. Add batter into a piping bag. Cut the tip off about 1/2″, and pipe shapes onto the parchment lined baking sheet keeping the tip in the center and squeezing out until about 1/4″ before the outside of the template. Then, pick up trays about 2″ from counter and let them fall down. Repeat. This helps to remove air bubbles from the batter. Let the batter sit about 45 minutes until a surface is no longer tacky when your finger touches it.
6. Preheat your oven to 350°f about 15 minutes before the rest time is finished. Place cookies in oven to bake, and then lower the temperature to 300°f. Cook for 18-20 minutes.
7. Let the macarons cool at least 20-30 minutes before decorating.

For the milk chocolate buttercream:

1. Heat milk in a small saucepan over moderate heat until hot. Whisk together yolks, flour, 1/4 cup confectioners sugar, and a pinch of salt in a bowl, then add hot milk in a stream, whisking. Transfer custard to saucepan and bring to a boil over moderate heat while continually whisking (about 30 seconds to one minute). Reduce heat and simmer, whisking, until mixture becomes very thick, about 30 seconds more, then transfer to a medium sized bowl. Cover surface of custard with plastic wrap and cool completely, about 45 minutes.
   
2. Add vanilla and remaining confectioners sugar to custard and beat at medium speed until combined well, then increase speed to medium-high and beat in butter, 2 tablespoons at a time, until smooth. Buttercream will look broken when mixing in butter but keep mixing and it will come together eventually!
3. Scrape down bowl. Add chocolates and beat until combined well.

For the assembly:

1. First, melt the 1/4 cup milk chocolate (or semisweet chocolate) in the microwave inside a microwave safe bowl, like glass, for 30 seconds. Stir and microwave again for an additional 30 seconds. Keep stirring and microwaving in short bursts of 15-20 seconds until melted and smooth.
2. Set aside 3 macaron halves for the bottoms. With the remaining three, dip the tops in the bowl of melted chocolate, letting any excess drip away, or edges smooth with a scribe or toothpick. Place dipped side up on parchment, and then sprinkle with chopped peanuts. Repeat with the remaining macarons. Use the remaining chocolate in the bowl to drizzle over the decorated tops.
   
3. Next, fill a piping bag with the buttercream. Cut the tip off about 1/4″ up from the tip and pipe the insides for the macarons.
   
4. Then, place the Snickers slices inside the ears, and in the center of the macaron. Pipe more buttercream if so desired. Place tops on and enjoy!