Preheat the oven to 180°C.
Sift the flour with the baking powder, and the cocoa.
Melt the chocolate and butter in the microwave or in a water bath and leave to cool.
In a bowl, mix the eggs with the sugar and vanilla seeds with an electric mixer until the mixture is frothy and clear. Still stirring, pour in the melted butter and chocolate.
Add the lemon zest and vanilla extract.
Add the flours, one spoon at a time, taking care to mix it well each time and alternate with the milk. Do not overmix the batter
Grease well and coat with flour a 24 cm cake tin
Pour the mixture into the cake pan and smooth the top with a spatula. Give the pan a couple of taps on the surface to release any bubbles.
Peel the pears and cut them into slices. Arrange ¾ of the cut pears on top of the batter and press them down.
Sprinkle the sliced almonds over the cake and top with the remaining pears
Bake in the oven for about 1 hour. It will be ready when the toothpick inserted into the centre comes out without wet batter.
Let it cool in the tin for 10 minutes then transfer it to the wire rack.