Preheat the oven to 200°C (Gas mark 4/400°F).
Crack and lightly whisk the eggs.
Peel and mash the banana and place in a mixing bowl. Add the yogurt, whisked eggs and vanilla extract. Stir well until completely mixed together.
Add the oats and baking powder. Stir well again until completely mixed together. Stir in the dried cranberries so that they are evenly distributed through the mixture.
Lightly oil 4 oven proof ramekins (I use a coconut oil spray for mine). Divide the mixture between the 4 ramekins, making sure that there is room for the mixture to rise in each one.
Place in the oven and bake for 20-25 minutes until golden and cooked through.
Meanwhile, prepare the toppings. Measure the yogurt and vanilla extract together in a bowl. Stir until completely combined.
Measure and spoon the Nutella into a disposable piping bag or small plastic bag. Snip off the corner then squeeze the Nutella down to the bottom, ready to pipe on top of your oats.
Peel and slice the banana.
Leave the baked oats to cool a little before serving.
To serve, top each bowl with a spoonful of the vanilla yogurt topping and sliced banana. Pipe over the Nutella (divided equally between the four portions) and finish with a generous sprinkle of chopped hazelnuts.