• Set the oven on a low heat: about 160℉/100℃ Fan to keep the crepes warm.
• Combine the crepe ingredients in a large bowl and whisk together thoroughly, until lumps are removed. Heat a large frying pan on a med/high heat.
• Melt the butter and use a pastry brush to brush a little over the pan before adding about 1/2 cup of batter to the pan. Swirl the pan to coat the base, then cook for about a minute on each side. If the pancake isn't loose, it may not be ready to flip. 
• Repeat for all batter, placing crepes on a plate in the oven as you go. Serve as they are with your toppings/fillings of choice:

For the Filling

• While the crepes stay warm in the oven, cook the eggs (over medium) - 1 per crepe. Do this by frying on a high heat, then flipping so that both sides are cooked. 
• On one half of each crepe, add about 1/2 tsp mustard, some baby spinach, a handful of grated cheese, a fried egg and some salt and pepper. Fold the untouched half over this and place in the frying pan (still on med/high heat). Let cook for a minute before flipping. Let cook another minute so that the edges crisp and the cheese melts. 
• Serve by folding again (into quarters) and place on a plate. Add a little more salt and pepper and serve immediately