When I make muffins, I mix everything by hand with a whisk. It seems to make a less dense finished product. Hope this helps!

Are you using fresh leavening agents? (Baking powder and/or baking soda.) They *do* expire,and if you're using old ones, they might not be doing their job of making the muffins light and fluffy.

Are you baking them long enough? If they aren't done in the middle, they'll fall after they come out of the oven.

If they're doughy AND the tops are sinking, I think underbaking is likely the culprit. In general, for perfect muffins (almost) every time, you will want to make sure you are

1. Mixing the dry ingredients in a large bowl, and the wet ingredients in a smaller bowl

2. Make a "well" into the middle of the dry ingredients, and when you're ready to mix, pour the wet ingredients into the dry and fold them together until they're just mixed. (Some lumps are OK, but over-mixing will make them dense and chewy) Generally 10 - 15 stirs.

3. Distribute the batter evenly into muffin cups, but fill them too full (just 3/4 full - about 1/3 cup of batter for your standard muffin tin)

4. Finally, make sure your oven is adequately heated and your rack is in the middle. Preheat your oven to 400 degrees for at least 20 minutes before baking (after it beeps, it should still have another 10 minutes or so to ensure it is properly heated). 400 should cover just about any muffin recipe but if you're really skeptical go ahead and do 375 instead. 15 minutes should cover you, but it may take up to 20.

Oh, and whatever you do, DON'T OPEN YOUR OVEN DOOR to check on them.... unless you're at the last few minutes of baking and don't have a window in your oven. Make sure you start checking on them at least 5 minutes prior to their stated baking time. If you're not sure that they're done, stick a toothpick in. It should come out mostly clean but with some crumbs clinging to it.

Let them cool for about 5 minutes in the pan then take them out and allow them to cool on a rack.

... Hope this helps :)

I recommend baking them at 400 degrees or higher, even if the recipe says to bake them at a lower temperature. You'll have to shorten the baking time slightly but since I've started baking muffins at 400F I always get nice fluffy tops. Good luck!

The previous posters all have good suggestions; I would try them.

I haven't tried this (not a muffin man/woman), but perhaps resting the batter in the fridge for an hour or more would help. This method works with pancakes and madeleines; I think it gives the gluten time to relax, the starch to absorb more liquid and for the leavening to create more bubbles. Furthermore, chilling the batter will help create a greater "shock" when they go into the hot oven and leads to crispier edges.

These are all such great suggestions! Thanks everyone, I feel newly motivated to try (yet) again...

I like to make sure the edges of the muffin tops start to get a little golden. Then you know they'll be nice and crispy. These are my absolute favorites, and they always come out crispy on top and moist and delicious on the inside.

I agree with Wee Eats - use the well method. It sounds like you're overmixing.

A few thoughts that have helped me, in no particular order: I am loyal to Clabber Girl baking powder and White Lily flour, sifted. I mix wet into dry and I don't use a lot of flour-about one cup at max for a dozen muffins. I use a lot of wet ingredients-vanilla yogurt, soaked raisins, thawed frozen overripe bananas, blueberries, milk. I have two muffin tins and have discovered that one takes two more minutes' cooking time at 400 degrees to get done. I do not overmix the batter, and I do let rest for 5-10 minutes before portioning. Finally, I let the muffins cool for eight minutes in the tin, then gently invert in a towel for eight minutes, then eight more right side up on the towel. These may not give the crusty top you're seeking but may help the quality of your finished product. Happy baking-

Use cake flour for a lighter texture, you could even try whipping the egg whites and folding them in to give it more lift.Sifting the flour will help a lot also.
The crispy top is sugar, sprinkle onto the wet batter so it soaks in just a little (or brush with a tiny bit of water) before baking.
The best thing you can do with any baked goods is to let the oven get nice and hot. If you don't wait long enough, it will bake at an uneven temp...

I'm probably guilty of overmixing, too. I know the theory, but get wary of any large lumps left in the batter and can't help mixing a bit more. I'd love to see videos or photos of what a proper muffin batter should look like!

do not overmix the batter - in my experience, this gives the end result the thick doughy texture. mix just enough to combine :)