To make the apple and blackberry compote, peel, core and finely dice the apples. Place them in a pan with the water and sugar and bring up to a simmer. Leave to cook, stirring every now and then, for about 10 minutes until softened; you may need to add a splash more water if it becomes too dry. Add the blackberries and cook for about 5 more minutes until soft but not mushy.
To make the waffles, Heat the oven to 140C/275F/gas mark 1 and place a couple of baking sheets in there. Whisk together the flour, sugar, cinnamon, baking powder, bicarbonate of soda and salt in a large bowl. In a jug, whisk together the milk, eggs and melted butter.
Gradually whisk the wet ingredients into the dry, adding a little at a time so the mixture doesn't get lumpy. Set the batter aside for 5 minutes while you heat your waffle iron.
Brush the waffle iron generously with oil then use a ladle to portion in the waffle batter. Cook the waffles according to the manufacturers instructions (all waffle irons vary), or until golden. Carefully transfer the cooked waffles to the baking tray in the oven to keep warm. Re-grease the waffle iron and repeat with the rest of the batter.
Serve the waffles topped with the warm compote and maybe a scoop of ice cream.