When you enter in your recipe in MFP, you could just put 20 servings and try and make 20 even cookies. That's definitely gonna get you close enough. But when I want to know EXACT numbers.. especially if some of the batter gets nibbled on before etc (what)... I use
this method to log my recipe and figure out the servings according to the weight of the pumpkin batter. I want to count every morsel of that batter so my numbers are totally accurate (I'm not always this obsessive.... but sometimes I am.)