Preheat oven to 180°C / 356 °F.
Combine rolled oats, milk, cinnamon, vanilla extract, sweetener and nuts in a bowl.
Taste the mixture and adjust to your preferred sweetness, then, if desired, add an egg and mix until combined. Egg is optional but is good for extra protein.
Transfer mixture into an oven-safe / cast iron pan. Pop berries and fruit on top and bake in the oven for about 20 minutes.
Drizzle nut butter and honey to serve!