Pasta with stuff on it.
Put pasta on to boil. While it cooks get the veggies ready. Toss the ones that need to be cooked into the water near the end of the cooking (snow peas, red peppers, green beans, broccoli, crushed garlic, etc.) Then add the other veggies and seasonings at the end, after draining (fresh herbs, chopped green onions, sun dried tomatoes, fresh tomatoes, parmesan, grated cheese, salt and pepper).
You can also make things like a cream or cheese sauce in on person portions using a small pan, or make simple sauces.
One trick I have for chicken: Buy boneless, skinless chicken breasts or thighs on sale. Take a heavy bottomed pan or skillet with a little olive oil. Put the whole pieces in and cook slowly on medium heat, covered for the first little while, until golden brown on both sides. They freeze really well, and you can grab one, microwave it, chop it and toss on pasta or salad.
Buy steak, cut into single portion servings and freeze. Then grill, bake or fry it with your seasonings of choice, and serve with a salad and bread and butter.
Tomato sauce and chili freeze well. I always make a big batch and freeze single serving portions to eat later - fast and nutritious.
Buy sausages and again, freeze in single portions. Then you can pull out one or two and grill it with some onions.
Individual pizzas. Again, I make the crusts myself, and freeze singly, and do the same with tomato sauce and the meat. Then you just have to pull them out, thaw the toppings, and add the veggies and cheese. Pizza made yourself can be a very healthy meal, if you don't load it with high fat toppings and go easy on the cheese.
Frozen dumplings are easy to cook for one person.