Place all the damsons in a medium pot with 50ml (1/4 cup) of water over a medium heat. Once the water in the pot starts to bubble, turn the heat down to low, cover with a lid and leave for 20 minutes. Check on them occasionally to give it a stir and make sure it's not catching on the bottom.
Preheat the oven to 180oC (350oF)/ 160oC (320oF) fan. Grease and line a 21cm (9-inch) springform pan with baking paper.
In a large bowl, beat together the softened butter, granulated sugar and almond extract. Add in the eggs one at a time, beating between each addition. Add the baking powder, flour and salt. Mix together until just combined. Pour into the prepared cake.
Once cooked, leave to cool with the lid off. When cool enough to handle, pick out all the pits from the damson compote - count them out so you don't miss any!!!
Spoon the cooked damsons onto the cake batter and spread out into an even layer. Bake for 20 minutes - it'll be a bit undercooked in the centre still.