One pot meals-

Nikkismission

This may be a stupid question, but I just can't mentally compute the answer in my brain lol ok, this is where I need the help and suggestions of my MFP family. A lot of the times I eat pre packaged meals or I do servings sizes, but I want to make one pot meals.... When I use serving size ingredients to make dishes and it's all combined into one... How do I now know whats a serving size and am I getting the right calorie intake for it?