Place the oven rack in the center of the oven and preheat to 350°F180°C.

Prepare 3 each, 9-inch (23 cm) cake tins by brushing bottom and sides with melted butter. Add a circle of parchment paper to the bottom of each pan and smooth out any air bubbles. Brush more melted butter over parchment paper. Dust lightly with flour. Tap any excess into the sink.

To a large mixing bowl add the ground pistachios, sieve cups cake flour, baking powder, baking soda and salt together.

In a separate mixing bowl or stand mixer, add the butter and beat until light and creamy. Add 1 cup (200 grams) sugar, oil, egg yolks, water, orange zest, and pistachio extract. Beat until the sugar dissolves.

Make a well in the center of the flour mix and add the wet ingredients in batches, mixing well in between additions until well combined. You can mix in natural green food coloring to give it the green pistachio color.

Clean the bowl from the wet ingredients and dry well. Add the egg whites and cream of tartar. * see note

Whip the egg whites using an electric mixer until they start to get foamy on a slow setting. Continue on the slow setting, add the 1/2 cup (100 grams) sugar in a fine stream down the side of the bowl to avoid deflating the whites. Once all the sugar is incorporated, turn the mixer on high and beat until stiff peaks form.

Carefully fold the egg white mixture into the the cake bater in batches.

Divide the batter between the 3 cake pans, smooth the tops and bake in the oven for 40 minutes until the tops are brown and a toothpick comes out clean when inserted in the center.

To a large mixing bowl add the heavy cream. Using an electric mixer, beat until it starts to stiffen. Slowly add the powdered sugar in small batches (to avoid getting covered in it), orange zest and juice. Whip the cream until stiff, do not over whip.

Place the first cake layer onto a cake stand.

Slide pieces of parchment paper under the cake, just around the edges to keep the cake stand clean of frosting.

Place the second cake layer on top of the frosting.

Slide pieces of parchment paper under the cake, just around the edges to keep the cake stand clean of frosting.

Place the second cake layer on top of the frosting.

Add 1/4 cup of frosting and spread evenly over the top of the cake. Place the third cake layer upside down (to get a flat top).

Using the rest of the frosting, cover the entire cake and smooth with an offset spatula or flat knife. Carefully slide out the pieces of parchment paper.