Had I known you were coming, I would have baked a cake.
If I had known you were coming, I would have baked a cake.
Both of these sentences are correct, and they both mean the same thing.
Hi Salvatore, I don't think it sounds natural in either because it 's grammatically incorrect. It should be:-
"If you had gone to Spain a year ago, you would speak Spanish very well now." This is known as the second conditional.
So this sentence will sound natural, not only in the UK and USA but in every English speaking country.