Line an 8 or 9 cm square pan with parchment paper, letting it hang over the edges for easy removal later.

In a blender, combine chopped strawberries and applesauce until smooth and well blended.

Transfer the strawberry-applesauce mixture to a heatproof bowl and sprinkle gelatin over the top. Whisk until thickened and no dry spots remain.

Place the bowl over a pot of simmering water, stirring gently until the gelatin dissolves and the mixture is warm. Remove from heat and let it cool for 10 minutes.

Using a stand mixer with a whisk attachment, beat the mixture on high speed for about 15 minutes until it has quadrupled in volume and resembles whipped cream with soft peaks.

Spread the fluffy mixture into the lined pan, smoothing out the top with a spatula. Chill in the fridge for at least an hour to set.

Once firm, slice the cake using a sharp knife and serve chilled. Add whipped cream or frosting of your choice if desired. Store any leftovers in the refrigerator.