Coffee Macarons with Nutella Butter Cream

I had 6 egg whites left after the Daring Kitchen Maple Mousse cup challenge, 2 egg whites from the cannoli shells and 4 egg whites from the mousse.

And it has been aged for a week in the fridge, I have been doing the Challenge a bit later again, but still, I managed to squeeze in the challenge just a week before I decided to use the egg whites to make macarons, what else can be better? When I do a bit of "busy" cooking, I tend to do it during the weekends when I don't need to be rushed.

Coffee Macaron Shells:
180g Aged Egg Whites
1/4 teaspoon salt
145g almond meal
287.5g icing sugar
90g sugar
15g fine instant espresso
10g cocoa powder

Process the espresso, cocoa powder, icing sugar and almond meal in the food processor until well combined and sift.
Whisk meringue, add salt to the egg whites and start bench top mixer on medium high, and gradually increase to high, and at the meantime, slowly add in all the white sugar.  Until meringue is hard peak.
Blend in the sifted dry ingredients into the egg whites, prepare the pipng bag.
I prefer to use my trust worthy silicon baking mats for macarons so piping is rather free-lance as I can't really draw circles on the silicon.

Leave piped shells to form crust for an hour, and tap the bottom of the trays to let air bubble out.  Bake in pre-heated 150C oven for 12-15 minutes.
Stand till cool, and remove.

Nutella Buttercream
125g butter
1 egg
1 cup nutella
2 heap tablespoons icing sugar (add more if desired)

Whisk egg with icing sugar till pale, and meanwhile, warm the butter (I used the microwave) to just melt.  Slowly drip the very warm butter into the egg mixture and whisk vigoriously - to make sure the egg won't scramble.  Once it's mixed, fold in the nutella, mix till smooth and silky.  Leave  in fridge to cool to just below room temperature and start to fill the macarons. 

I freezes the macarons if I can't use them up and they do freeze well.  Great to bring some to work the next day as treats!