I just use water or LC milk for liquid. Or egg! Egg gives your muffin puffiness.
1 whole egg is a lot, you really would only want 1/2 an egg for most bowl muffins, unless you're going for an omelet type of bowl muffin.

Today I made a mother of a Bowl Muffin Omelet. I took just under 1/3C CQ, 1T of flax meal mixed it with two lightly beaten eggs, 2 strips of bacon cut into small pieces and a good serving of cheese, some pepper. Nuked for about 2.5 minutes and topped with butter. Wow! It's like an egg-mcmuffin or one of those egg-cheese-bacon croissants from fast food restaurants. Super delicious!

Hey, if you can find some frozen raspberries (unsweetened) you should toss a few into that raspberry concoction. That'd be sooooo tasty. Just throw them in frozen.