Grease a ring cake tin (22 cm Ø; 2 1⁄2 l capacity) and dust with flour. Preheat oven (electric cooker: 175 °C/circulating air: 150 °C/gas: see manufacturer). Peel, quarter, core and cut pears into small pieces.
Sprinkle with lemon juice.
Separate eggs. Beat the egg white with 3 tbsp. cold water until stiff, adding sugar at the end. Stir in 8 egg yolks briefly. Mix 150 g flour and starch, sieve over it and fold in carefully.
Fold in pears. Put the dough into the tin and smooth it down. Bake in a hot oven for about 40 minutes.
Take the cake out of the oven and let it cool down. After about 10 minutes, carefully turn out onto a cake rack and let it cool down. Dust with icing sugar and cocoa.