Preheat oven to 300°F. Get out two sheet pans and line with baking parchment. Using a pencil and a 6-inch diameter bowl or ruler, trace 3 6-inch circles on the papers—2 on one sheet, 1 on the other. Return parchment to pans, pencil-side down.

Add a couple inches of water to a saucepan and bring to a boil on the stovetop. Once boiling, lower heat to simmer. This will serve as a double-boiler for the next step.

Add egg whites, sugar, and pinch salt to the metal bowl of an electric mixer and whisk by hand to combine. Using a hotpad to protect your hand, hold this bowl over the saucepan of water, whisking until sugar dissolves and the mixture is quite warm, about 5 minutes. Remove from heat, dry outside of the bowl, place in the stand mixer with whisk attachment, and whisk on high for 15 minutes, until mixture is cool and billowy.

Sprinkle the hazelnut flour and cocoa over the meringue and using a large spatula, gently fold to combine.

Transfer meringue to a piping bag fitted with a plain ½-inch diameter tip (Ateco 806). Pipe spirals to fill the 3 circles traced on parchment. Pipe any remaining meringue into small kisses or sticks. Place pans in preheated oven, turn off heat, and the dacquoise will be perfectly baked and dried out by morning.