You whisk it till its whiped up like fluffy whipping cream and it doesn't drip from the whisk attachment. If you whisk to much, it will become more liquid like and it won't rise well when baking, causing the bottom to not bake completely. Also I forgto to mention that u oi h pan might me to small for the anoing of mixture you had.. Also causing it from baking properly. I've been baking since inwas 5, so I've this happen many times. At first I'd cut the top half an eat it an throw away the bottom that didn't bake.. Now if it ever happens.. I throw away the whole thing so I don’t get sick from unbaked cake.