Learning Kitchen Chemistry with a Whoopie Pie Fail

Calling all expert bakers and kitchen chemists! Help!

I don't know what technically constitutes a "Whoopie Pie", but they always look so poofy. Mine, notsomuch! See?...

My basketball whoopie pies looked a little bit like slightly puffier oatmeal cream pies, not that rounded whoopie pie look! 
When I first tried making these, I had the oven on convection bake--epic fail. I used two different pans (stoneware and metal). On the metal pan (on convection bake), my little scoops completely flattened and ran together. 

In addition, the outside was done was before the inside and even the "poofy" ones on the left flattened as they were cooling. Not pretty.
So, I tried again. Normal bake, only stoneware. The result was much better. No running all over. Looked very puffy while baking, but had to increase the baking time to get the inside cake to be done. Once out of the oven, they started flattening some. No longer that puffy dome shape. The taste was good--they were still soft and fluffy/chewy tasting. But, just didn't have that puffed up look I was expecting.

 So, this is where I want YOUR ideas/tips/suggestions/advice! :) Anyone out there a whoopie pie baking extraordinaire?!
Where did I go wrong? The baking pans? The cake mix? The oven temperature? The cooling method? 
PLEASE share your thoughts! :)