I wouldn't worry about the 3 year old's diet, as long as you are providing a variety. I also wouldn't revolve a family's menu around what a 3 year likes or doesn't like.
Are you a working mom? Slow cookers are quite handy, as well as those foreman grills.
If you like lasagna, an easy recipe calls for layering sauce and ravioli in a pan and baking it.
Chicken breasts, roasted in a pan with your choice of herbs (like rosemary, oregano),and butter is always good.
roasted potatoes, cut up, toss with butter, herbs, salt and pepper
try using the search function for ideas, there are also mommy blogs on the net that have some good menu suggestions, just google it.