1. Preheat oven to 250°F.
2. Beat together egg whites, cream of tartar, and sugar until stiff but not dry.
Fold in nuts.
4. Divide mixture into (2) two 9” x 13”-rectangular pans lined with parchment paper. You can also use 4 (four) 8" or 9" round pans. It's up to you :)
5. Bake in the preheated oven for one hour or until golden.
6. Transfer on wire racks. Cool in the pans for 5 minutes. Invert then carefully remove the parchment paper. Slice the meringue into two pieces. (Now you will have four meringue pieces)
7. Completely cool on wire racks.
FOR THE BUTTERCREAM:
1. Boil together sugar and water until threadlike at 220°F.
2. Beat egg yolks until thick and fluffy.
3. Continue cooking the syrup until 240°F.
4. Pour hot syrup into egg yolks in a stream. Beat until cold.
4. In another bowl, beat the butter until light.
5. Add egg yolk mixture then add vanilla. Beat until creamy.
6. Fill the meringue layers with mixture. Place on top of each other.
7. Spread more buttercream mixture on top and sides of the meringue layers.
8. Sprinkle with cashew nuts.
9. Freeze for few hours then serve.
10. Enjoy :)