Once you've tried this, I think you'll decide that every cake you make needs custard nuggets.
For the custard
180ml whole milk
Seeds from ½ vanilla pod
50g icing sugar
2 tbsp corn flour
For the apples
30g dark soft brown sugar
5 eating apples, peeled, cored and quartered
1 tbsp butter
2 splashes of calvados or brandy
80g pecans, roughly chopped
3 tbsp maple syrup
For the cake
150g dark soft brown sugar
75g plain flour
2 tsp baking powder
Make the custard first. Whisk all the ingredients in a saucepan and place over a medium-high heat. Stir until it almost boils, the turn the heat down, still stirring, until it is very thick and you can no longer taste the cornflour. Transfer to a bowl and place in the fridge to cool and set.
Preheat the oven to 180C/350F/Gas 6. Line a 25cm cake tin with baking paper.
For the apples, place the sugar and a tablespoon of water in a large frying pan over a medium high heat and cook until it begins to bubble and the sugar has dissolved. Stir in the apples and butter along with a pinch of salt and cook for a few minutes before adding the calvados. Cook for 5 minutes until the apples begin to soften. Stir in the pecans and the maple syrup and cook for another 3 minutes, then leave to cool.
For the cake, cream together the sugar and butter until slightly lightened. Beat in the eggs one at a time, then fold in the flour and baking powder.
Pour into the cake tin, then add teaspoonfuls of the set custard and fold the little nuggets into the batter. Spoon the apples and pecans on top, lightly pushing them below the surface. Place in the oven for 30-35 minute until golden and just firm. Serve warm.