Cooking with chronic fatigue
I also have neurological disorders that cause symptoms similar to chronic fatigue. Here are a few tricks that have helped me with cooking dinner: 


Make sure your kitchen is set up in an efficient organized way. Keeping your kitchen well organized is key to reducing the time you spend cooking.  Take your limitations into account when organizing your kitchen.  For instance, if bending down flares up your symptoms, keep the items you use the least in the lower cabinets.
Purchased pre-chopped veggies 
Use tin foil / parchment paper on cookie sheets and casserole dishes as much as possible.  This will limit clean up.
Try sitting as much as possible while cooking. Here is a stool that rolls around.
As alluded to in other responses, try recipes that allow you to prepare much of the meal ahead of time - while you have more energy.
Look for recipes where the majority or all of the cooking is in the oven as opposed to over the stove.  While the cook times may be similar, you can take a load off if you are primarily using the oven. 
Once every 3 months I cook up (in the oven) and shred a 'big buy' of chicken and store it in the freezer. I use the cooked meat for risottos, soups, pasta dishes that call for cooked chicken. 
Finally, here is a resource for quick recipes: allrecipes