Dark brown sugar gives the oats a deep toffee like flavour that light brown sugar or honey can't. You can sub for either of those though, if you don’t have dark brown sugar it will just alter the taste slightly.
You can boost the protein by adding ½ a scoop (15g of vanilla or caramel protein powder) to the oats. Stir in once the oats are cooked off heat until well combined.
You can replace the topping of caramel sauce and yoghurt with caramel protein pudding.
For extra depth, you can stir in a touch of coffee or vanilla extract.
For a pudding-like flavour, you can stir in a small knob (around 5g) of light butter spread.