Pop the ground almonds and icing sugar into a food processor and give it a blitz for a minute to make sure you have an extra fine consistency, and then sieve into a large bowl.

Make sure for this next part, that the bowl that you are using is extremely clean.  If there is any oily residue, the egg whites won't stiffen into nice firm peaks. Whisk the egg whites, the caster sugar (1 tablespoon at a time) and pinch of salt using an electric whisk until you form these peaks. I've popped some pictures below so you can see what you are looking for.  Add in the vanilla extract and whisk again.  You should be able to turn the bowl over your head without any mixture falling onto your head and you ending up with literal egg on your face. If you are wanting to add some food colouring so that you end up pretty pink macarons, then pop a few drops in now. 

Using a spatula, gently fold in half of your almond mixture into the egg whites. Then add in the other half and mix again. A wee test to make sure that it is all incorporated, is to try and create a figure of 8 with the mixture without it breaking.  

Next put your mixture into a piping bag (if you don't have one you can always just use a spoon or even an ice cream scoop but they might look a little bit messier) and pipe out about 24 circles with a diameter of about a 2 inches or so onto a baking tray lined with baking paper. Again there is a pic below so you can see what I mean. 

Now is where you can let out any anger that has been building up throughout the day and whack the tray (literally whack it) on the counter top about 4 times to get rid of any air bubbles. Then leave them to rest for an hour until they form a dry layer on top. This is what helps them to rise up and not just spread out into a big ol' mess.

Bake them in the oven at 150C (140C fan, gas mark 2) for 16 minutes. 

Leave them on a wire rack to cool.

To make the vanilla buttercream filling, just stir together softened butter, icing sugar, splash of milk and the vanilla. Super simple.

To make the chocolate buttercream it is almost exactly the same but add in melted chocolate. And finally to make the mocha just replace the splash of milk with 2 tablespoons of strong filter coffee. 

Using a piping bag, pipe the buttercream onto the macarons and then sandwich two of them together and voila you have perfect yummy macarons that look like you have nipped to a French patisserie to get them.