I have never made an upside down cake, and inspired by last weeks Great British Bake Off I set about making this Blueberry and Elderflower Upside Cake from Scandilicious Baking by Signe Johnson. Ingredients Oil for greasing 400g Fresh or Frozen Blueberries 50ml Elderflower Cordial 4 Medium Free-range Eggs 250g Caster Sugar 1 tsp. Vanilla…