Could I substitute Vanilla Extract for the Vanilla Essence and if so, how much Extract would I use in place of the Essence?

Regarding Vanilla essence. This has two meanings. In Britain, vanilla essence is the same as America's imitation vanilla extract, which is a synthetic, chemical replication of the pure, natural extract. Elsewhere, vanilla essence may mean a highly concentrated (and 'expensive') form of pure vanilla extract. Pure vanilla extract, as the name suggests, is the extract of vanilla bean pods made by immersing vanilla pods in alcohol, (I make my own using vanilla pods and vodka or Cognac.) Either way, it would be a one for one substitution.

I tried this recipe, and I must not have done it right. The consistency was THICK, like thin cookie dough, but not like usual cake mix. I used vanilla extract instead of vanilla essense, could that be my problem? it also didn't rise very well, and I was using a 6'' pan. It tasted like normal white cake, and was totally easy to make, just wished it baked up better, please help!