In a suitably sized bowl, whisk together 1 cup beaten eggs and 1 cup flour. I find this easiest by adding the flour, forming a well in the centre and pouring in the eggs. Whisk from the centre out until lump free.
Whisk in 1 cup milk and add a good pinch of salt and pepper. Cover and pop in the fridge and allow to rest overnight (or as long as you have time for, even 30mins is great to get the batter cold).
Heat your oven to 220c/430f and pour 1 tsp of oil into each slot of a cupcake tray. Pop in the oven for 15mins or until the oil is smoking hot. *must be piping hot*
Take batter out the fridge and pour it into a jug.
When the oil is very hot, evenly, quickly and carefully pour your batter into each slot, ensuring you don't fill each slot all the way. Also make sure you don't splash any batter between slots, this pulls down the batter when it tries to rise. I prevent this by holding a tbsp under the jug in between pouring to prevent it dripping everywhere. It's important to do this step quickly, you need the oil to stay piping hot!
Roast in the oven for 15-20 minutes or until they have risen and are a deep golden brown colour. (timings will depend, just be vigilant). Do not open the door before 15mins, this will allow cold air to rush in and potentially deflate the Yorkshire puddings. Drain away any oil that may have got stuck in the centre of the Yorkshire pudding.
In my opinion the best Yorkshire Puddings are ever so slightly charred around the edges and crazy looking!