I Want Better Batter

I attempted making whoopie pies today. Seeing as I didn't even know about them until last week I was apprehensive about making them. The batter seemed to be extremely thick and the baked sponge mushroomed instead of turning out with a shape similar to macarons. So I'm guessing I need more experience.
Any how, I've baked these for tomorrow and I may have to blip the finished product!
I also keep getting these dark spots on my photos. My lens is clean on both ends so I can only assume it's on the mirror inside. Disaster. I'm too scared to clean it in case I scratch it and make it worse!