I try to save a bit of our tea to give mine the next day, because he eats so early. Occasionally if I'm tired I'll eat early with him and then go to bed :o If it's something suitable for freezing I take a couple of baby portions off and freeze them to cover days we have something unsuitable or I forget. Otherwise a quick tea is things like:
Chicken nuggets/fish fingers/sausage/veggieburger (small portion obv) with microwave veg (I like the Bird's Eye steam fresh bags, they don't go soggy or taste horrible like most frozen veg). Maybe a potato smile or two.
Baked beans with toast to dip in, sometimes cut up cold cooked sausage microwaved in with the beans.
"Picky tea" ie little things cut up cold and put on a plate, I usually do bits like sweetcorn, peppers, cucumber, cherry tomatoes (quartered), little squares or shredded bits of ham and cheese, crackers, grapes, apple.
Microwave scrambled egg with frozen spinach cube. The spinach mixes into the egg as it cooks and then I cut up a cherry tomato into 8ths and stir it in after cooking to warm. Although he's gone off this recently.
A very German one :o (We live in Germany) but Schupfnudeln/pancakes with apple sauce. You can do it with Gnocchi. Sounds really weird but buy the ready made Gnocchi or unsweetened pancakes, a bit of apple sauce on a plate, warm them through slightly and dip the doughy noodly bits into the sauce before eating.
Rice pudding, just that, with or without fruit puree/tinned fruit. Again, very German but I've adopted it.
I don't eat macaroni cheese because I don't like it but that would probably be a quick/easy one as well. I've even seen mug recipes for it...
Mini pizzas you can get from Sains/Tesco etc I can't remember now who does them. Or cheese on toast "pizza" - add a layer of tomato puree and ingredients under the cheese. DS1 used to like that.
Easy pasta - Cook pasta, meanwhile in another pan fry a bit of onion and garlic and chicken. Add tinned tomatoes to chicken pan and stir through. Add cooked, drained pasta. You can also use a jar of pasta sauce and add cold cooked chicken, cold cooked sausage or drained tinned tuna. Sweetcorn gives it a bit more colour/variety/veg if you want that.
Noodles similar - make up half a pack of instant noodles without the flavour sachet (way too salty), meanwhile in a small frying pan, fry some onion/peppers/carrot/very thin sliced meat/etc depending on what you have and what LO likes. Mix together, cool (you can also rinse the noodles in cold water when you drain them) and serve. DS2 likes to pick up the noodles very slowly one by one and enjoys that. I make this for myself too but I put the flavour sachet in and add soy sauce and chilli to mine.