To a mixing bowl, add the butter, sugar, and salt. Mix on medium-low speed until the mixture is “creamed”, which means lighter and a bit fluffy. Since this is a roll out dough, you don’t need to mix it for several minutes until it is very fluffy like you would for a cake. Look for a completely combined mixture with no lumps of butter or clumps of sugar.

Add the egg and vanilla and mix until emulsified. The mixture will be smooth, thick, and a bit shiny. All at once, add the flour, cocoa powder, hazelnut flour, and baking powder. Mix on low until the dry ingredients are nearly combined and there are no dry, floury spots. Be careful not to over mix the dough!

Drop the dough onto a piece of lightly floured parchment paper. Sprinkle a bit more flour on top of the dough lump before covering it with another piece of parchment paper. Use a 1/4″ guided rolling pin to roll out the dough.

Refrigerate the dough for at least a half an hour to two hours to chill the butter in the dough. This makes it so much more workable and helps prevent spread in the final cookies. If you’d like to work ahead of time, leave the dough (well wrapped) in the fridge for up to three days. If you’re in a rush, freeze the dough for ten to fifteen minutes.

Once the dough has chilled, and you’re ready to start cutting cookies, preheat the oven to 375 F. Grab your cookie cutters and cut shapes from the dough, dipping the cutters in flour if they are sticking to the dough. Place the cut shapes on a parchment lined baking sheet and pop in the freezer for five minutes before baking. This helps the cookies retain their shape. Don’t skip this!

Bake the cookies for 6-8 minutes for smaller cookies, and 8-10 minutes for larger cookies. Keep an eye on them, and bake them until the tops are no longer shiny. Don’t over bake them, or they won’t be soft.

Once they’re done baking, let them cool on the cookie sheet for a few minutes before transferring them to a wire rack to cool completely. If you move them too soon when they’re piping hot, they could break easily.

Re-roll the dough scraps, preferably up to two times. If the dough is very soft after rolling, pop the dough in the freezer for five minutes to chill before cutting cookies again.

While the cookies are baking, make the icing. Weigh eight ounces (one cup) of icing into a small bowl. To the bowl, add 1-2 Tbsp of Dutch cocoa powder (using a fine mesh sieve to sift the cocoa powder into the bowl of icing) and a splash of hot water. Mix it together until it is fully combined and the mixture forms a paste. Add it to the bowl of icing and stir to combine. Thin the icing out to your desired consistency and use as usual.