Place your pie dish / skillet / baking pan in the oven then set temperature to 200°C (fan-forced, or 220°C regular) and allow to warm up (this will make the pan nice and hot).
In a mixing bowl beat the eggs then add milk, sugar and vanilla. Add in flour and mix well. The batter should be quite runny.
2 eggs, 100 mL milk, 1 tbsp sugar, 1 tsp vanilla, 100 g gluten free flour
When the oven reaches temperature remove the pan (oven mitts on!) and grease with butter all over.
1 tbsp butter (for greasing)
Pour in all the batter and put it in the oven to cook for twenty minutes.
Notes
If you omit the sugar and vanilla this actually becomes a Yorkshire pudding recipe!