In a saucepan, cook green grapes, sugar, and lemon juice over medium heat.

Stir occasionally until the water visibly reduces.

Add 1-2 drops of green food colouring (optional) and mix well.

Transfer to a bowl, cover with cling film, and refrigerate.

Place eggs and sugar in a bowl over a saucepan with hot water. Keep whisking until the sugar dissolves and the mixture reaches 40°C (104°F).

Remove from heat, add vanilla extract, and beat on medium speed until the batter is foamy and forms ribbons.

Sift in all-purpose flour and cornstarch. Gently fold in with a spatula.

Melt butter and milk over hot water. Mix a small portion of batter into it, then combine it with the rest of the batter.

Pour into a greased and lined 7-inch cake pan. Bake at 170°C (350°F) for 35 minutes.

Let the cake cool for 5 minutes before transferring to a wire rack.

Place a bowl of whipping cream over another bowl filled with ice and chilled water.

Beat the cream while gradually adding powdered sugar until peaks form.

Divide the cream into two equal parts. Add green food coloring to one portion and mix well.

Trim the brown top of the cake and slice it into three equal layers.

Pipe uncoloured whipped cream between layers and add green grape compote.

Refrigerate for 20 minutes.

Spread green-coloured whipped cream over the cake and decorate with white whipped cream, fresh grapes, and mint leaves.

Refrigerate again for 20 minutes if the cream starts melting.