Start by whisking 5 large eggs with 1 cup of granulated sugar until the mixture is light and fluffy.

Add 3/4 cup of softened unsalted butter into the egg mixture and combine until smooth.

In a blender, puree 3 mandarins with their skins and mix them into the egg mixture gently.

Then, sift in 3 cups of all-purpose flour and add 2 teaspoons of baking powder before folding everything together until just combined.

Preheat your oven to 350°F (180°C).

Pour the batter into a greased cake pan and spread it evenly.

Bake for 30-35 minutes or until a toothpick inserted into the center comes out clean. Allow to cool.

In a mixing bowl, beat 3/4 cup of unsalted butter at room temperature until creamy.

Gradually add in the can of sweetened condensed milk and continue to beat until combined.

Stir in 1/2 teaspoon of vanilla extract, followed by the finely chopped 2 mandarins. Make sure to add the juice from these mandarins to the cream for extra flavor and moisture.

Finally, mix in 3/4 cup of chopped walnuts until well incorporated.

In a small bowl, combine the juice of 3 mandarins, 2 teaspoons of sweetened condensed milk, and 1/2 cup of water. Stir well to blend.

Once the cake has cooled, carefully slice it into layers.

Using a brush, soak the layers with the prepared syrup to keep them moist.

Spread a generous amount of the cream between the layers, and add more cream on top and around the sides of the cake.

For decoration, sprinkle chopped cake pieces around the edges and top it off with the zest of 1 mandarin.

This will not only enhance the look but also add a nice citrus aroma. Serve the cake chilled or at room temperature and enjoy this delightful mandarin treat!