Cut the apple in half and place one half to the side for now. Remove the core from the other half and cut it into pieces.
Add the apple pieces and raisins to a pot and caramelize everything for one minute with the golden syrup.
Stir the eggs, sugar, and vanilla extract together. Sieve the flour, ground almonds, cinnamon, and baking powder onto the mixture before carefully folding everything together.
Heat up the butter in a pot or microwave. Add the melted butter to the batter and stir until the mixture is creamy.
Peel the other half of the apple, remove the core, cut it into pieces, and add them to the creamy batter.
Pour the batter onto the caramelized apple and raisins in the pot. Leave everything to cook for 25 minutes on a low heat.
Take a plate and turn the cake onto it. Use a cloth or oven gloves when handling the hot pot. Pour some more golden syrup on top if desired.
