These muffins are fantastic. Our kids devour them. The first time we made them together I had each one mix up their own without knowing what would happen when we put them in the microwave. Instant hit. I called them "Magic Muffins."
My only additions are that I use a full tablespoon of coconut oil rather than a teaspoon. Usually I make the basic cinnamon version and add 2 T of frozen berries. Then I up the cooking time to 1:30; sometimes a bit longer. It's pretty hard to screw these up. Just make sure the top is done and you're probably fine. Mess around with it. I also think it's worthwhile to mix it up in a separate bowl and then put it in the coffee cup- and no need to spray the cup with oil, they pop out just fine without it.
Another great version I recently made up is to replace the 2t of cinnamon with cocoa powder, and add 1 T chocolate chips and 1t vanilla extract. That's delicious. Try apple chunks, pumpkin spice in place of cinnamon, or skip the cinnamon and do some lemon zest and juice etc- there are so many ways to change it up. The recipe sans spice or other flavors is pretty bland, so you can do what you want with it.
Just one more way to get some flax.