Prepare a baking sheet with parchment or silicone mat (if you have enough, prepare 2 baking sheets).

Over a large mixing bowl on a scale, sift almond flour until you reach 105g. Discard any large pieces of almond flour. Repeat with the confectioners sugar. Whisk the almond flour and confectioners sugar until very well-combined. Set aside.

Add egg whites, white sugar, and egg white powder to the bowl of your stand mixer, and whisk together. Place the bowl over top of a simmering pot of water (bain-marie), ensuring a tight seal and ensuring that the bottom of the stand mixer bowl is not actually touching the water.

Continuously whisk the mixture while it heats up over the bain-marie, heat the mixture until it reaches 140°F (60°C). When temperature is achieved, remove the bowl from the simmering water pot and place onto your stand mixer, fitted with the whip attachment.

Beat the mixture, starting on low. Once soft peaks have been formed, increase the speed to medium. Once medium peaks are achieved, increase the speed to high. Beat on high until stiff peaks have formed. Add in the vanilla, and beat until just combined.

Remove the bowl from the stand mixer, and place a sieve over top. Pour the dry mixture into the sieve, then sift the dry ingredients into the meringue.

Fold the dry ingredients into the meringue. I like to scrape around the sides of the bowl in an entire circle, and then cut through the centre – similar to the Greek letter phi which looks like this: Φ

Be gentle and careful not to overmix or over-deflate the meringue. The mixture is ready to be piped when it ribbons off your spatula, meaning that the batter, when lifted with a spatula, should keep flowing off the spatula in ribbon shapes nonstop, without drizzling off too quickly. If it is coming off in large V shaped chunks it still needs to be folded further. Another test is the figure 8 test: If you can lift some batter up and use it to draw several figure 8’s without the stream breaking, it is ready!

Add mixture into a piping bag with medium sized round tip. Pipe small circles of batter onto a cookie sheet fitted with a silicone baking mat or parchment paper. Ensure piping bag is held straight up and perpendicular to baking sheet. Using a stencil or a macaron mat makes this process much easier and fool proof, I try to make my macarons around 1½” in diameter.

Tap the baking sheet multiple times against counter to remove any air bubble from the macarons. If some air bubbles still remain, use a tooth pick to gently poke them out. Sprinkle the macarons with the rainbow sprinkles.

Preheat oven to 300°F, or 275°F for convection oven. While oven is preheating, allow the macarons to sit and form a skin. This skin will ensure the macarons bake up and not out, giving them those classic “feet”. This skin should form anywhere from 8 minutes to an hour. You know the macarons are ready to be baked when you can touch them lightly without having the batter stick to your finger. Keep checking them to see if they have formed a skin– overly dried macarons are just as much of a problem as under-dried macarons!

Bake for 15-20 minutes. Your bake time will depend on the size of your macarons. Check at 15 minutes, and if they are not ready then keep checking every minute. The macarons are ready when the tops are firm and do not move around their base at all.

Allow the macarons to cool completely before attempting to remove them from the sheets/mats/parchment. When cooled, find “perfect pairs” of macaron halves and set aside to be filled.

Add the boxed cake mix to a microwave safe bowl. Microwave for about 1 minute and 30 seconds, stirring every 30 second interval, until the cake mix reaches 170°F. Set aside to cool for 10 minutes.

Add the butter to your stand mixer fitted with the whip attachment. Beat until light and fluffy – about 3 minutes. Add in the cooled cake mix and confectioners sugar in intervals, until very well combined and smooth.

Finish by adding the cream, vanilla, and food colouring, until well-combined. Add to a piping bag fitted with a star tip.

Pipe the birthday cake buttercream onto ½ of the macaron shells (bottoms of perfect pairs), then top each bottom with it’s corresponding top. Place into the fridge overnight to mature and meld together.