Try looking for a book called "Cooking Well for the Unwell" by Eileen Behan. She has a section in it about making every bite count calorie wise. She is an RD and her book has sections on basically every situation we encounter as CDer's. I have found it very helpful. I don't think it is still in print, but I got a used copy from Amazon for about $4.
This book has been SUCH a help to me since my surgery! Just this minute I have Behan's pear bread pudding in the oven for a late breakfast. Last night, I made her sausage, apple, squash dish. While I'm slowly putting the weight on, she's helped me to 1-think of foods to eat in dfferent combinations (I was stuck on chix broth) and 2-explains so well how foods work and why we might not want to or can't eat. This was especiallly effective when I just couldn't eat when I got home. I have to substitute a lot of canned items for her fresh.
She has a lot of quick ideas for adding calories or protein or whatever it is you need. I got the book on amazon.
Having my mom cook with and for me really has helped me. Even if you feel totally well, having someone help create a few meals for the freezer could be a help b/c the food is already there and you may be more likely to eat.
Finally, the small, frequent meals/snacks are truly helping me.
24+ years with Crohn's/colitis; fistulizing crohn's; ileostomy and proctocolectomy; propranolol and xanax; been on a ton of crohn's meds; praying to get through each day.