Wash the pears, grate them dry and cut them in half. Remove the core with a melon cutter. Bring 500 ml water, pear syrup, liqueur and 1 teaspoon cinnamon to the boil in a wide saucepan. Place the pears in the hot stock with the cut surface facing downwards, cover and simmer at medium heat for 25-30 minutes.
Remove the pears carefully and let them cool down.
Put 300 g flour, sugar, 50 g cocoa, baking powder, 2 teaspoons cinnamon and baking soda into a mixing bowl and mix. Add eggs, buttermilk and oil to the flour mixture and mix with the whisk of the hand mixer.
Pour the dough into a greased, floured box form (approx. 11 x 30 cm; approx. 1.75 litres capacity).
Mix 1 tablespoon flour, 1/2 teaspoon cinnamon and 1 tablespoon cocoa in a bowl. Turn pear halves in it and press them almost completely into the dough. Bake in a preheated oven (electric cooker: 175 °C/ convection oven: 150 °C/ gas: see
manufacturer) bake for about 1 hour. Take out and let cool on a cake rack.
Roughly chop the chocolate and melt over a warm water bath. Carefully remove the cake from the mould and place on a plate. Decorate with chocolate.