I have a couple of recipes that ALWAYS overflow over the sides of the cake pans. Red velvet is the worst offender, but depending on how full I fill the pans it can happen to any type of cake.
I recently switched the recipe that I use to make vanilla cakes, and I think that it's also an overflower. I don't want to change the leavening amounts because I like the texture of the cake, but I also don't like having to clean batter off the bottom of the oven while I'm baking.
I've started collaring the pans when I make certain types of cakes, but it might be good to do it for everything. I've noticed that the cakes that I bake with collars tend to bake a little taller, so the batter must like the parchment that I'm using to make the strips.
When the cake bakes up slightly taller than the edge of the pan it also makes it much simpler to level the layers, too. Try it and see if your cakes bake up a little taller.
Kara Buntin owns A Cake To Remember LLC, online cake supplies at www.acaketoremember.com and www.acaketoremember.etsy.com