Great suggestion from LilacMom - I also do little pizzas like that with naan bread (which I buy frozen from Trader Joe). The kids can also help build the pizzas which is fun.
Some of my other go-tos:
1) Grilled chicken - I buy an organic brand of grilled chicken strips (no breading) fully cooked and frozen - I just heat a little bit of veggie or chicken stock in a saucepan and thaw & rehydrate them a little. Delicious!
2) Pasta - I cook dried pasta and then add a little butter, garlic powder, and tiny bit of salt w/parsley flakes. My 2 kids (including my not quite 2 year-old) LOVE it!
3) Edamame - I pop them out of the shell for the little one but my 4 year-old squeezes them out himself.
4) Grilled cheese - you can also add bits of tomato and/or ham.
5) Sweet potatoes - cut into wedges and do fries, or bake until soft and mash (skin on or off depending on what your kids like) - add a little bit of butter, brown sugar and organic cinnamon and bake again for a few minutes until bubbly.
5) Homemade apple sauce - roast your own apples (@ 350 degrees until soft) then peel, core & puree with or without organic cinnamon. You can also freeze into ice cube trays for a yummy frozen treat.
6) Frozen sweet peas - it's weird - toddlers love them. Frozen.
7) For the 2 & 3 year-old, sweet corn on the cob. Wrap cobs (husks on) individually in foil and roast them at 350 for 30 minutes - perfect every time.
8) Wraps - I melt cheese on an open face tortilla in the oven and slip in little bits of red pepper - wrap it up and serve like a taco or burrito once melted.
9) Scrambled eggs with tiny cubes of pancetta and cheddar or gruyere cheese melted in. Yum!
10) English muffins toasted with peanut butter & jelly or peanut butter & honey.
11) I was a vegetarian for a long time so I'm still not totally adept at cooking red meat - I try to go to our local butcher or Whole Foods once every so often and get a high quality cut of organic beef to serve them (so I don't screw it up!). :)
12) And you can't go wrong with adding fresh, whole foods as side dishes - like blueberries, strawberries, bananas, cashews, walnuts, dried cranberries, carrot sticks (mine like them with hummus).