Preheat oven to 170 C / Gas 3. Prepare two loaf tins with cooking oil spray.
In a small bowl, make the cinnamon sugar by mixing together 4 tablespoons dark brown soft sugar and 1/4 teaspoon ground cinnamon. Set aside.
Mix the eggs, vegetable oil, sugar, courgette and vanilla extract together in a large bowl; add the raisins. In a separate bowl, combine the flour, bicarbonate of soda, baking powder, salt and 1 teaspoon cinnamon.
Whisk the flour mixture into the courgette mixture, stirring until almost all the lumps are gone. Divide the batter between the two prepared loaf tins; sprinkle the tops with the dark brown soft sugar-cinnamon mixture.
Bake in the preheated oven until a cocktail stick inserted into the centre comes out clean, about 1 hour. Cool in the tins for 10 minutes before removing to cool completely on a wire rack.