Preheat oven to 160ºc/Fan 140 ºc/Gas 3 and line a baking sheet with the macaron template or baking paper.
Sift the icing sugar, cocoa powder and salt together in a food processor then mix in the ground almonds. Pulse the mixture 10 times.
Whip the egg whites on low to a soft peak consistency and slowly add in the sugar a little at a time.
Add the vanilla to the meringue during this soft peak stage. Then continue whipping on medium-high until you get stiff/firm peaks.
Now add in 1/3 of the almond mixture and start folding gently until incorporated. Continue until all the almond mixture is used up and the batter forms a ribbon effect.
Pipe small rounds about 1.5" in diameter onto the baking paper or use a template if needed (you can download or find these easily online).
Give the sheet a tap on the table a couple of times to remove any air bubbles. Use a tiny amount of water on your fingertip to smooth any rough spots if needed.
Set these aside to dry uncovered until a crust forms on the surface. About 30 minutes - 2 hours.
Bake at 160ºC for about 14-15 minutes or until lightly browned. Cooled Macarons should pull away from the parchment paper without sticking. If they are sticking, they haven’t been baked enough.
Leave these to cool fully before removing from the parchment and filling with ganache. At this stage the unfilled Macarons can be stored in the fridge for up to 5 days or frozen for 6 months in an airtight container.
For the Filling
Pop all of the ingredients into a heatproof bowl and microwave for one minute (a few seconds longer if not quite melted). Let the mixture sit for around 5 minutes then whisk until smooth, put into the fridge for 20 minutes and whisk again until smooth. You are looking for the texture of smooth peanut butter.
When you’re ready, fill a piping bag with the ganache mixture and pipe onto the flat side of one of the macaron cookies then sandwich together with another... Voila!