SO here is the rule I find about doubling consonant
if a word ends with a short vowel sound plus a consonant, and the stress is on the last syllable, then the final consonant is doubled if you add an ending that starts with a vowel.
I find this rule to be much more powerful than the one I learned at school, aka:V+C, But the rule doesn't seem to apply to cooking, which is not doubled. Is this a contradiction of the rule I quoted above? (I am not so sure about the short vowel but, but simple Google tells me that ʊ in cooking is indeed a short vowel. )
Also, if cooking is indeed an exception to this rule, are there any other similar exceptions that I should be aware of?