Blackberry upside down cake (gf/df)

250g ripe blackberries
150g self raising flour (gluten free or normal)
150g golden caster sugar
150g unsalted butter, margarine or vegan butter (at room temperature)
1 tsp baking powder
¼ xanthan gum (if using gluten free flour
2 large eggs (at room temperature)

1. Preheat the oven to 180 degrees C (160 fan), and grease and line a 22cm square cake tin.
2. Put all the dry ingredients into a large mixing bowl, sieving the flour as you add it. Stir well to combine.
3. Add the butter or margarine plus the eggs and mix well with an electric whisk or wooden spoon.
4. Scatter the blackberries across the bottom of the cake tin and then gently add the cake mix
5. Place on the middle shelf of the oven and cook for approximately 40 minutes or until golden brown.  Check with a skewer to see if the cake is fully cooked through.
6. Serve warm with ice cream or custard.  Equally delicious cold with a cup of tea.