Line a large baking sheet with parchment paper and position two 7-inch pastry rings on it, ungreased. Preheat the oven to 465°F / 240°C.

Add the pistachios to a food processor and pulse them until finely ground, but be careful not to process them too long, or you’ll end up with pistachio paste.

1 ¼ cups Pistachios

Add the flour and powdered sugar to the ground pistachios and pulse until everything is combined. Set aside.

½ cup Powdered Sugar, ⅓ cup Cake Flour

Ensure the egg whites are at room temperature, then whip them with the cream of tartar and a pinch of salt using a stand mixer or electric whisk.

1 teaspoon Cream of Tartar, ¼ teaspoon Salt, 5 large Egg Whites

Once the egg whites start to froth, gradually add the sugar, one tablespoon at a time, whipping for 30–60 seconds in between each addition.

⅝ cup Granulated Sugar

Once all the sugar is incorporated, the meringue should be thick, glossy, and free of any graininess. Continue whipping until stiff peaks form.

Once the meringue is ready, gently fold in half of the pistachio flour mixture. Be cautious not to deflate the meringue too much.

After it’s incorporated, add the remaining pistachio flour and fold until completely mixed.

Divide the dacquoise batter evenly between the two pastry rings and spread it out as flat as possible.

Place the dacquoise in the oven and immediately reduce the temperature to 350°F / 180°C. Bake for 15 minutes.

After 15 minutes, turn off the oven and slightly crack the oven door. Allow the dacquoise to sit inside for an hour before transferring to the countertop to cool completely in the pastry rings.

Once fully cooled, use a sharp knife to carefully run around the edge of the pastry rings and gently release the dacquoise.

Place the egg yolks in the bowl of a stand mixer fitted with the whisk attachment. Whip on medium-high speed until the yolks become very pale, about the color of butter (around 5 minutes).

8 large Egg Yolks

In the meantime, heat the sugar and water in a small saucepan over medium heat until it comes to a boil. Use a candy thermometer to monitor the temperature, aiming for 240°F / 115°C.

¾ cup Granulated Sugar, ⅓ cup Water

Once the sugar syrup reaches the right temperature, reduce the mixer speed to low and carefully pour the syrup into the egg yolks in a slow, steady stream, avoiding the sides of the bowl or the whisk.

The bowl of the stand mixer should feel warm once all the syrup is incorporated. Increase the mixer speed to high and whip until the bowl returns to room temperature, which should take about 10 minutes.

When the bowl feels cool, begin adding the softened butter, a small chunk at a time. Allow each addition to fully incorporate before adding the next.

2 ½ sticks Unsalted Butter

As you add the butter, the frosting may initially look runny, but don’t worry. Continue whipping, and it will eventually thicken up and become glossy. If it doesn't thicken, increase the mixer speed to high and continue for another minute.

Once all the butter is incorporated, add the vanilla and pistachio paste, and whip on high speed for an additional minute. Taste the buttercream and decide if you want to add the salt for a perfect sweet and salty contrast once it’s on the dacquoise.

1 teaspoon Vanilla Extract, 4 tablespoons Pistachio Paste, ¼ teaspoon Salt

Place one dacquoise layer on a cake board or serving plate.

Transfer the pistachio French buttercream to a piping bag, snipping the end off. Pipe small blobs of buttercream around the outside of the dacquoise.

You can pipe blobs all over the layer or just focus on the outer ring, then spread frosting in the middle of the cake.

Place the second dacquoise layer on top of the buttercream and repeat the process, piping blobs of buttercream all over the top of the cake.

Decorate the outside of the cake with chopped pistachios for a finishing touch.