Start by preheating your oven to 350°F (175°C). Grease and line the bottoms of two 8-inch round cake pans with parchment paper. It’s a little step, but it makes all the difference when it’s time to take the cakes out.

In a large bowl, combine the flour, sugar, butter, eggs, baking powder, salt, and chopped walnuts. Using an electric mixer, beat everything together until smooth. It’s an all-in-one method, so don’t overthink it—just mix until there are no lumps.

Divide the batter evenly between the two prepared pans, smoothing the tops with a spatula. Bake for 25–30 minutes, or until the cakes are golden and a toothpick inserted into the center comes out clean. Let them cool in the pans for 10 minutes, then transfer them to a wire rack to cool completely.

In a heatproof bowl, whisk together the egg whites, sugar, water, and cream of tartar. Place the bowl over a pan of simmering water (make sure the bottom doesn’t touch the water) and whisk continuously for about 7–10 minutes until the mixture thickens and forms stiff peaks. Remove from the heat and continue whisking for another minute to cool slightly.

Place one cake layer on a serving plate and spread a generous amount of frosting on top. Place the second layer on top and spread the remaining frosting over the top and sides, smoothing it out for a neat finish.

Arrange the walnut halves on top of the cake for a simple yet elegant decoration. Chill the cake in the fridge for about 20 minutes to set the frosting before serving.