I am making around 36 cupcakes next week and the only recipe I can find is for 12! Can I just mix 3 times this recipe in the bowl or will it effect the cooking time? If not does someone have a recipe that will make 36 cupcakes? I am in the UK so the amounts in grams or oz would be great.
If you have pans to cook 24 cupcakes at one time, and if they will fit in your oven, then make 2X your recipe. Mix and bake the third dozen separately. That's a conservative plan that will succeed regardless of what your recipe is.
Cooking time for 24 in the oven at the same time is a few minutes more than for 12.
But if you already have a good cake recipe, just use that. There is nothing inherently special about "cupcake" batter, you simply adjust the cooking time for the much smaller cakes.