Mine absolutely love the pudding.
Basically, get a box of the vanilla instant pudding. Mix it according to directions but using whole milk. Add one raw egg yolk and mix with an electric mixer. It will not set as regular pudding but will be a little runny. It'll keep for a couple of days in the fridge. Feed it several times a day.
I'd do the boiled chicken...no seasoning. I've had to hand feed Gracie since she refuses to eat from a bowl...such a diva. I also hold a bowl of broth up since she won't drink it if it's laying flat on the ground. Spoiled? Probably...but with a nursing mother, you do what you have to do in order to keep up her strength, milk and health.
Also, vitamins are really good.
Here is a link for fat balls to help your female gain weight. My dog absolutely LOVE these (recipe #1)! I have this site bookmarked.
http://www.lowchensaustralia.com/health/diet4.htm