Preheat the oven to 190°C (375°F/Gas 5). Grease a 20cm (8inch) spring-form cake tin.
Sift the flours, sugar, baking powder and cinnamon into a large bowl. Return the husks to the bowl. Toss the blueberries through the flour mixture. Whisk together the egg, milk, oil, vanilla and lemon zest. Pour into the dry ingredients and stir to combine. Pour the mixture into the prepared tin.
To make the topping, combine the pecans, brown sugar, flour and blueberries in a bowl and sprinkle evenly over the cake. Drizzle the oil over the topping. Bake the cake for 50–55 minutes, or until a skewer inserted into the centre of the cake comes out clean. Serve the cake warm with a dollop of cream.