Bring milk and 40 g sugar to the boil. Add semolina while stirring, bring to the boil once. Remove from the heat, cover and let it swell for about 5 minutes. Roast walnuts in a pan without fat.
Sprinkle 60 g sugar over it, let the sugar caramelise. Place on a piece of aluminium foil lightly coated with oil and spread. Let it cool down. Cut the bananas into slices and sprinkle with lemon juice.
Separate the egg. Beat the egg white with salt until stiff, pour in 25 g sugar. Whisk the egg yolks with 100 g cream, mix with 2 tablespoons of semolina, stir into the remaining semolina. Coarsely chop the walnut caramel.
Fold the beaten egg white into the semolina. Layer semolina with bananas and walnuts in 4 glasses. Whip 100 g cream until stiff, fill into a piping bag with star-shaped spout. Pour tuffs into the glasses, decorate with mint and serve immediately.