Tart apples, sweetened and topped with a crisp, buttery crumble.

Ingredients
3-4 apples, peeled and cubed (cooking or dessert apples)
2 tbsp butter (plus extra for greasing)
third cup sugar
½ lemon, zest and juice of
1 cup blackberries
Crumble Topping
1 cup porridge oats
½ cup all purpose flour
quarter cup sugar
third cup butter, melted
Optional: ½ cup nuts (chopped hazelnuts)
To serve: whipped cream 

1. Preheat oven to 350° Fahrenheit (180°C) fan. Grease a medium size ovenproof dish.
2. In a saucepan, gently melt the butter and sugar. Add in the cubed apples and lemon juice.  Cook for 5-7 minutes on a medium high heat (the apples should still be al dente and retain their shape).
3. Remove from the heat and gently fold in two thirds of the blackberries until their juices start to run into the apples. Taste and adjust to your desired sweetness adding more sugar if needed. 
4. Transfer the fruit filling into the greased ovenproof dish. Dot the...