In the microwave, in a small bowl melt the butter, honey, sugar and peanut butter. In a large bowl, mix together the protein shake powder, muesli, oats and nuts. Stir the wet ingredients into the dry ingredients and mix in the egg. (Add more honey or oats if the mixture looks too dry/wet at this point.)
Pat mixture into a baking dish and bake in the preheated oven for 15 minutes, until golden brown on top.
Cut into breakfast sized portions while hot then leave to cool. In the morning grab a bar, stick it in the microwave for 10 seconds and you're good to go!
I started with this recipe and experimented until I got it just the way I like it!