Preheat the oven to 200C/400F/Gas 6.
For the baked apple, melt the butter in a small ovenproof frying pan. Add the apple, flesh-side down, and fry for two minutes.
Turn the apple over, sprinkle with the cinnamon and sugar, then transfer to the oven to bake for 10-12 minutes, until softened and cooked through.
To make the sauce, place the sugar, cinnamon and butter into a frying pan and heat for 3-4 minutes to caramelise.
Add the double cream and continue to heat to thicken the sauce.
To serve, place the baked apple in the centre of a warm plate and pour over the butterscotch cinnamon sauce.