Can I bake this as a single layer 9 x 13 cake instead?
Yes, but the baking time (start checking the cake at 25 minutes) will vary and you’ll likely need only half the amount of chocolate buttercream.
Can this be made into a 3-layer cake?
Yes but you’ll need to use smaller diameter cake pans like 6” pans. This will also alter the baking time so start checking the cakes at 25 minutes.
Can I skip the parchment paper lining on the bottom and just use extra non-stick cooking spray?
No, the parchment paper is highly recommended so the cake doesn’t stick to the bottom of the pan. You’ll still use non-stick cooking spray inside both pans but over top of the parchment paper lining on the bottom.