Yesterday when I made my muffins I noticed that the sides and the bottom of my muffins are dark. I used a nonstick muffin pan for baking my muffin recipe. I have no idea that what is causing this problem. On my friends suggestion I made it on low flame today but there was no escape to the situation. I was wondering if anyone can tell me here that what the problem with my recipe is. Shall I fill the muffin cups half and then see the results?