To make the crêpes, put the flour, sugar, eggs and milk into a blender and blend for 20-30 seconds until well combined and no lumps remain.
Pour into a jug and rest the batter for 15 minutes.
Place a non stick pan over a medium heat and allow to fully heat through. Use a small amount of butter to grease the pan, then add enough batter to cover the base- swirling to make sure there are no batter-less areas.
Leave to cook for a minute or so- you want the edges to crisp up and pull away from the pan and the crepe to be golden brown.
Flip the crepe, and cook for a further minute on the other side.
Stack the crepes, with sheets of greaseproof paper in between until you’ve used all your batter - you should have 6.
To make the sauce finely grate the zest of one orange, and make strips with a zester from the other. Squeeze the juice from both oranges into a large frying pan. Add the grated zest (leave the zested strips for later), the butter and sugar and simmer for 5 minutes or until a little thickened and syrupy. Add the orange liqueur then either tilt the pan over the direct flame, or set the alcohol alight with a match. Leave to burn off, then give everything a good stir.
One by one, add the crepes into the hot pan then fold into quarters making sure the sauce coats the surface evenly. Allow to re-heat fully then serve each crepe with some hot sauce and garnish with orange zest.
If desired, warm up a little extra orange liqueur over a direct flame in a ladle. Set alight, then drizzle over each crepe and watch the alcohol burn off before tucking in.