Preheat the oven to 180°C/160℃ fan/350°F/gas mark 4. Line a 23 cm/9 in square cake tin with baking parchment.
To make the crumble topping, stir together the flour, sugar and cinnamon in a bowl, add the melted butter and stir until no dry patches remain. Place the bowl in the fridge while you make the cake batter.
125 g (1 cup) plain (all-purpose) flour, 60 g (5 Tablespoons) light brown soft sugar, ½ teaspoon cinnamon, 75 g (⅓ cup) vegan butter
Drain one of the tins of peaches really well then pat as dry as possible with kitchen paper. Cut into chunks then toss with a Tablespoon of flour to coat.
one 411 g tin peach slices in fruit juice, 1 Tablespoon plain (all-purpose) flour
Tip the entire other tin of peaches into a blender, including the liquid. Add the oil, vanilla extract and vinegar and blend until smooth.
one 411 g tin peach slices in fruit juice, 110 g (½ cup) neutral oil (I use olive), 3 teaspoons vanilla extract/vanilla bean paste, 1 ½ teaspoons vinegar
In a large bowl, whisk together the flour, cornflour, caster sugar, baking powder, bicarbonate of soda and salt.
270 g (2 ¼ cups) plain (all-purpose) flour, 50 g (5 packed Tablespoons) cornflour (cornstarch), 200 g (1 cup) caster or granulated sugar, 2 ½ teaspoons baking powder, ¼ teaspoon bicarbonate of soda (baking soda), ¼ teaspoon table salt
Pour the blended peach mixture into the dry ingredients and stir with a balloon whisk until no dry lumps remain. Gently fold in the flour coated peaches.
Pour the batter into the lined tin. Scatter over the crumble topping and the chopped hazelnuts.
40 g (¼ cup) roughly chopped hazelnuts
Bake for 45-50 minutes until firm and a skewer inserted into the centre comes out clean. Leave to cool in the tin for about 20 minutes then carefully lift the cake out of the tin and place it on a wire rack to cool completely. Once cool, store in an airtight container in the fridge.