blueberry muffins

I'm not sure about this recipe for blueberry muffins from the hummingbird bakery cookbook.  The first time I made it, they turned out like this-

They said it made 12.  It makes 24, which isn't necessarily a bad thing, but just seems like a big difference.  When I told lulu I was making blueberry muffins she asked that I make them "not flat" again.  They weren't flat, but they still weren't right.

Nice, but did I forget to put the blueberries in?

No, but, every single one of them sunk to the bottom.  The up side is that cj wanted no part of the blueberries, so he and lulu split them in half.  He could have the top and she could have the bottom.

I'm sticking with this recipe.