Hazelnut flour: Make sure to sift the hazelnut flour BEFORE measuring it to use in the recipe. I had to sift about 60 grams of hazelnut flour to obtain 30 grams of hazelnut flour that would be fine enough to be used in the macarons. If the flour is too coarse, you will run into several issues such as misshapen shells, batter that's too thick and won't flow, feet that separate from the top of the shells. I used Bob's Red Mill Hazelnut Flour, which claims to be finely ground, but really wasn't.
Egg white powder: Egg White Powder is not the same as meringue powder. Egg white powder is made of only egg whites. They help with getting fuller shells, and specially when adding a lot of food coloring to the batter, because they make the shells dry faster. I recommend experimenting with it if you can find it. I use 4 grams for each 100 grams of egg whites.
Food coloring: Make sure to use gel food coloring. If you are a beginner macaron baker, I recommend going easy on the food coloring, as it can alter your batter a lot, and it can take extra mixing time, specially if you continue to add the food coloring as you do the macaronage.
Batter thickness: When compared to almond flour macaron batter, this hazelnut macaron batter is a bit thicker, so you might think you have to continue folding when in reality it's just the nature of this batter to be on the thick side due to the hazelnut flour. As long as you can draw a couple of figure 8s with the batter falling off the spatula, and also as long as the falling batter is incorporating nicely with the batter on the bowl, you are good to go. Watch my video on this page or on YouTube which will show you the proper consistency for the batter.
Scale: Please use a scale when measuring the ingredients for accuracy.
Macaron amount: it will vary greatly depending on how big you pipe the shells, and on how runny or thick the batter is.
Baking time/temperature: Baking time and temperature will vary according to your own oven. I recommend experimenting with your oven to find out the best time, temperature, position of the baking tray.
Oven thermometer: Make sure to have an oven thermometer to bake macarons. It’s one of the most important things about making macarons. Home ovens aren’t accurate at all at telling the temperature, and even a slight 5 degree difference can make or break your whole batch.
Tray rotation: Lots of bakers don’t have to rotate the trays 180 degrees in the oven every 5 minutes, but I do have to with my oven, or I will get lopsided macarons. Please adjust this according to your oven.