I also made chocolate hazelnut macarons for the party. Only I didn't have enough time to fit in both the macarons and the cupcakes, so I just brought over the cupcakes and finished making the macarons after I got back. Recipe for the cookies are the same as for these, except replacing 1/4 cup of almond flour with 3 Tbsp of cocoa powder instead. The filling is the same Nutella buttercream from the cupcakes.
They were...alright but not fantastic. I may have let them sit out for too long before baking. hence the enormous foot and a super crispy shell. But another part of it may also be that the shell goes wonky when you sub in cocoa powder :(