Cupcake woes

I use an ice cream scoop that hold 3 tablespoons for my standard size cupcakes. I used to eyeball it but then some cupcakes were bigger than others, or looked wonky. That would be my tip. Use something to accurately measure the batter you are putting in your liners.

I don't know your recipe, but you said chocolate cupcakes gave you trouble. Do you have success with other cupcake flavors?

I also use an ice cream scoop that holds about 3 tbs on batter... (the kind with the lever on the side that releases the ice cream). I would fill about 2/3 full. You can fill a pastry or zip lock bag with the batter and snip the corner off to fill the liners too.

If you are looking for a domed cupcake I preheat to 400 degrees then turn down to 350 when I put the cupcakes in the oven.

Sinking could be due to underbaking... I have some recipes that give me a slight divot in the middle but I cover it with frosting so it's not a big deal.

I did an experiment recently with my cupcake pans as I was having the same problem.

I have a few cupcake pans that I purchased when I started out. They were relatively cheap and not commercial grade. I found that I was mixing and matching cupcakes with different batches to make them all even. Then bought 2 expensive, kitchen grade pans and low and behold that is why my cupcakes were never even. Anyway, I used the exact same amount of batter that I always use (ice cream scoop) and baked them side by side Sure enough, the cupcakes in the kitchen grade pans were perfectly even, and the other ones were super wonky.

I recommend getting good cupcake tins and I am sure that will help with them being uneven.