Start by preparing your baking pans for the meringue. Line three baking pans with parchment paper and draw outlines for either 10x6 inch rectangles or 8-inch circles. Grease the parchment lightly.

Preheat your oven to 285°F (140°C) and gather your ingredients.

Beat egg whites with cream of tartar until soft peaks form. Gradually add granulated sugar, continue beating until stiff peaks form, about 5 to 7 minutes. Fold in chopped roasted cashews and vanilla extract.

Evenly divide the meringue mixture among the prepared pans. Bake for 40 minutes to 1 hour until golden brown and dry. Leave in the oven to cool gently.

In a saucepan, combine sugar and water, heating until the sugar dissolves. Beat egg yolks until thick, gradually drizzle in warm syrup, then add butter and vanilla extract until fluffy.

Once meringue layers are cool, assemble by layering meringue and buttercream on a serving platter. Finish with buttercream and sprinkle extra cashews.

Freeze the assembled dessert for at least 2 hours before serving.