1. Give it a bash
For a long time I made my macarons as the recipes stated, even letting them rest, yet they always came out cracked on top and I couldn't work out why. Then one day, I was looking up tips for macarons and it said to hit the baking tray to remove excess air bubbles. So, I made another batch and dutifully did as it said and, although still not perfect, the macarons didn't crack on the top - just by hitting the tray.
The consistency of the macaron batter should be just right: not too stiff and not too loose. I've heard it described as 'magma', you'll know it's there when if the batter is dropped from a spatula it can sink back into the mixture in 10 seconds. You should err on the side of too stiff: too thin and it will just spread out like a pancake.
When piping the macarons, make sure they are far enough apart that they won't spread into each other, 1-2 cm is about right: there's is nothing more annoying than an otherwise perfectly good batch of macarons which has merged into one.
Rhubarb and blood orange macarons
Macaron shells (adapted from Tartelette):
90g egg whites (about 3)
50g caster sugar
Zest of an orange
1/4 teaspoon ruby food colouring paste
200g icing/powdered sugar
110g ground almonds
1. Line 2 trays with baking parchment. Whisk the egg whites until they reach stiff peaks. Whisk in the sugar, a tablespoon at a time, until the mixture is stiff and glossy then whisk in the orange zest and food colouring.
2. Whisk together the icing sugar and almonds then fold into the meringue. When dropped from a spatula, the batter should sink back into the mixture in 10 seconds.
3. Preheat the oven to 140C/285F. Pipe into small rounds then leave to form a 'skin', so that when touched they do not feel sticky. Bake for 20 minutes.
Rhubarb and blood orange buttercream:
125g rhubarb chopped into batons
Juice and zest of 1 blood orange
Few drops of vanilla extract
3 egg yolks
100g room-temp butter, cut into cubes
1. Put the rhubarb, vanilla, and orange juice and zest in pan and cook until the rhubarb is tender. Blitz until smooth.
2. Combine the rhubarb purée, egg yolks and sugar and cook until the mixture thickens and becomes custard-like. Leave to cool.
3. Beat the butter until light then add the rhubarb, a bit at a time until smooth.
Pipe into the filling into the macarons and serve
Till next time, happy baking!