Preheat the oven to 180°C/350°F/Gas 4. Grease the side of a 22 x 7½cm loose-bottomed baking tin with dairy-free margarine.
Put 50g of the margarine in a saucepan and heat over a gentle heat until melted. Stir in 100g/3½oz/scant ½ cup of the sugar or xylitol and heat for 2 minutes until completely dissolved. Pour over the bottom of the tin and arrange the peach slices on top.
Using a hand-held electric whisk, beat the margarine and sugar or xylitol together in a large mixing bowl until light and fluffy. Gradually beat in the almond extract and then the eggs, one at a time. Sift the flour, ground almonds, baking powder and xanthum gum into the bowl and carefully fold in with a metal spoon. Pour in the lemon juice and dairy-free milk and stir in gently.
Pour the mixture into the prepared tins, over the peaches, and spread it evenly with the back of a wooden spoon. Bake for 30–35 minutes until golden brown, risen and firm to the touch and a skewer inserted in the centre comes out clean. Remove from the oven and leave to cool in the tins for 5 minutes. Then remove the side of the tin and quickly turn the cake over onto a plate. Slide onto a wire rack.
Heat the jam in a saucepan over a gentle heat until warm and, using a pastry brush, brush over the peach slices. Leave the cake to cool completely.
Recipe by Grace Cheetham at https://www.gracecheetham.com/gluten-free-dairy-free-upside-down-peach-cake