Apple and rhubarb crumble - 9Kitchen

Ingredients

• 3 Granny Smith apples, peeled, cored and roughly chopped
• 3 stalks rhubarb, cut into 3cm pieces
• 2 tbsp caster sugar
• 1 tsp lemon zest
• 1 tbsp water
• ½ cup rolled oats
• 2 tbsp flour
• ¼ cup brown sugar
• 40g butter, chopped
• 1 cup blackberries