I also didn't have any chocolate chips on hand, but I did have a semisweet vegan chocolate bar that didn't taste so good by itself. So, I cut up the chocolate bar into smaller chunks and used this in place of the chocolate chips. The recipe calls for 1.2-2 cups of chocolate, but I only used 1 cup and it was still a little too chocolate-y for me.
I'm not a big fan of bananas, but I actually really like these muffins. You can't even taste the banana...just the way I like it!