Preheat the oven to 180C/350F and spray an 8x8 inch square pan with cooking spray.
Place oats, sugar, spices, salt and baking powder into a large bowl and mix briefly to combine.
Add in the chunks of orange and raspberries and stir briefly, just to distribute the fruit around.
Place milk, egg and vanilla extract into a large jug and lightly beat until the egg is completely incorporated.
Pour the milk mixture into the fruit and oat mixture and stir gently until well combined. Mixture will be quite runny at this stage, that's fine.
Tip the entire mat mixture into your prepared pan and smooth into a level layer with a spatula/wooden spoon.
Place inthe oven for 25-30 minutes, until golden and the milk is absorbed and it feels slightly firm to the touch.
Leave to cool in the pan for at least 15 minutes before serving.
You can also leave it to cool in the pan completely, then serve cold. Baked oatmeal can be re-heated in the microwave the next day.
Store the baked oatmeal in an airtight container, in the fridge for 2 days.