I'd bet it's your baking powder. I did a side by side comparison of baking powders a long while back. I used all the same ingredients and technique in all the batches, only different baking powders. I found that when using Bob's Red Mill I got even color, Bakewell's Cream light spots, Rumford's medium spots and Hain Pure Foods dark spots. I still use Hain's for everything because it had the least bitter "baking powder" taste.
4/18/08 at 7:03pm