Preheat the oven at 180° Celsius
Break the eggs and separate the yolk and the white. Put the yolk in a big bowl and the whites in a smaller one. Beat the yolk with the sugar and the cinnamon until you got a smooth mixture.
Add the melted butter and beat until smooth. Add the flour little by little and beat until you got a beautiful and homogeneous mix. Set aside.
Beat the eggs whites with a pinch of salt until it forms stiff peaks, add the whites very slowly to the preparation with a wooden spoon.
To finish, add the medlar purée to the preparation and mix very gently just enough to incorporate the purée until it forms a sort of marble pattern.
Put the dough in a buttered loaf tin (the preparation has to fill three-quarters of the pan). Sprinkle with the roughly chopped almonds. Bake for about 50 minutes. Check the baking by planting a the tip of a knife in the middle of the cake if it's came out dry, it's ready!