Watermelon Cake | No-Bake Fruit Birthday Cake

Cut a single 8 cm-thick slice from the middle of the watermelon; slices closer to the ends will not stand upright. Lay the slice on a cutting board and remove the rind with a knife, working from top to bottom until no white pith remains. You should have a rind-free cylinder with a flat base; white patches on the sides will not hold the yogurt and will show through the coating.

Set the cylinder on a plate lined with paper towels. Press a towel against the top and sides to dry them, changing the towel 2 times. Touch the surface with the back of your hand; it is ready when your finger stays dry. Yogurt will not cling to a wet surface and will slide off within the first minute.

Use a spatula to mix the strained yogurt, powdered sugar, and vanilla powder in a bowl. The consistency is right when the mixture falls from a spoon in a thick ribbon without breaking. If it runs quickly, the yogurt has not been strained enough; strain it in cheesecloth for another 20 minutes.

Quarter every grape lengthwise: first cut it in half lengthwise, then cut each half lengthwise again. Do not leave even one grape round. Hold the strawberries by their stems and cut each lengthwise into four slices. Peel the kiwi and cut it into 5 mm-thick half-moons. Place each type of cut fruit on separate paper towels to absorb excess juice.

Place the cylinder on a serving plate. Starting at the top, spread the yogurt coating down the sides with a spatula, making it about 5 mm thick all over. Arrange the fruit from top to bottom and add the mint leaves last. Before slicing, dip the knife in hot water and dry it so the yogurt does not drag along the cut edges.