Heat oven to 190⁰ gas 5
Place the butter and sugar in a bowl and beat until light and creamy. Gradually beat in the eggs, adding a little flour if the mixture curdles. Fold in the flour and cinnamon. Spread the mixture into the prepared tin.
Peel, halve and core the apples. Run the prongs of a fork 0ver the top to score them and arrange on top of the cake mixture. Bake for 1 hr. To 1hr. 15 mins. Or until the skewer comes out clean (if not, cover the cake with baking paper and cook for a futher 10 mins or until cooked. Brush the cake with the apricot glaze and sprinkle with the demerara sugar, before serving.