Cut the vanilla pod lengthwise and scrape out the pulp with a knife. Bring milk, vanilla pulp and pod, 1 pinch of salt and 3 tablespoons of sugar to the boil. Remove vanilla pod, add semolina while stirring, bring to the boil once.
Remove from heat, cover and leave to swell for about 5 minutes.
Separate eggs. Beat the egg whites until stiff, adding 1 pinch of salt and 1 tablespoon of sugar. Whisk the egg yolks and stir into the semolina. Fold the beaten egg white into the semolina.
Score apricots crosswise with a knife, blanch with boiling water, rinse cold and peel the skin. Halve and stone the fruit.
Preheat oven (electric cooker: 200 °C/circulating air: 175 °C/gas: see manufacturer). Grease a wide casserole dish (approx. 1.25 l capacity). Coarsely crumble the rusk. Approx. 2⁄3 of it under the semolina. Put the semolina into the dish.
Spread the apricots on top. Sprinkle with almond slivers.
Bake the casserole in a hot oven for about 30 minutes. Take out, sprinkle the remaining rusk over it and dust with icing sugar.