Pulse almonds and hazelnuts in a food processor to obtain a coarsely ground texture.
Beat the egg whites on low-medium speed until they start to foam. Add cinnamon and vanilla extract. Add the sugar, a tablespoon at a time, Whisk until you obtain stiff glossy peaks.
Transfer this mixture to a heat proof bowl and place over a pot of hot, barely simmering water. This mixture needs to be stirred for about 15 minutes.