Prepare one large piping bag for macarons. Drop a large round tip (Wilton 1B or similar) into the bottom of the piping bag and use scissors to cut around the middle of the piping tip then simply pull off the tip of plastic. Make sure the piping tip is secure in the bag then twist the bag a few times to block anything from leaking while filling. Set aside.

Place powdered sugar and almond flour in the bowl of a food processor and process until the almond flour mixture is a fine powder. Now sift the almond flour and powdered sugar mixture 3 times through a sieve or metal mesh strainer.

Add egg whites and cream of tartar to the bowl of a stand mixer fitted with the whisk attachment and set on medium speed.

When the beaten egg whites start to look foamy, lower the mixer speed and slowly add the granulated white sugar while the mixer is still running. Increase the mixer speed to medium-high.

When the meringue (the egg mixture) turns white, lower the mixer speed and add vanilla extract. Increase mixer speed to medium-high and mix for approximately 6-8 minutes until stiff peaks form. To test this, remove the whisk attachment, swirl it in the bottom of the mixer a few times and turn it over. If you have a glossy peak that sticks straight up, the meringue is ready. Soft peaks will flop over at the top. If this happens, mix for a few more minutes and try again.

When the macaron batter is ready, add to the prepared large piping bag.

To pipe macarons, hold the piping bag straight above each circle, not at an angle. Use your bottom hand to guide the piping process and the top hand only to squeeze batter from the bag. Pipe until your template circle is filled (or until your desired size). Stop squeezing the piping bag and flick your wrists to separate the piped macaron from the piping bag without creating a peak.

Lift each cookie sheet approximately one foot from the table and drop it three times.

Optional: Use a toothpick to pop any air bubbles on the tops of the macarons and swirl to smooth out the batter.

Make the buttercream and prepare the chocolate-hazelnut filling while the macarons dry, bake, and/or cool.

Bake one tray of macaron shells at a time for 12-14 minutes, rotating trays halfway through.

To test doneness, place your finger on the top of one of the macaron shells and wiggle. If the top feels like it wiggles separate from the bottom (or the “feet” of the macaron), keep baking. Macarons should be done before shells start to brown.

Let macarons cool on trays and then flip over the parchment paper and peel the parchment off of the macarons rather than peeling the macarons off of the parchment.

Using a stand mixer fitted with the paddle attachment or using a hand mixer, cream the butter. Sift powdered sugar and add in a few batches. When this mixture is smooth, add salt and vanilla extract and mix on medium-high for a few minutes until the buttercream is fluffy and lightens in color, scraping down the sides of the bowl as needed.

Fill one piping bag with buttercream and one with chocolate hazelnut spread.

Pair up macarons and flip half of the shells over. Pipe an open circle of buttercream along the outer edge of each of the flipped shells then fill the open circle with chocolate-hazelnut spread. Place the remaining half of the shells on top of the filled shells and gently press and twist very slightly to secure the top of the macaron in place.