My kitten apparently loves veggies! How much can she safely have?

Before I say anything else: I am not planning on switching my cat to a plant-based or vegetarian diet. She has a high protein, meat-based diet and I'm only planning on feeding her veggies as a treat or maybe mixed in with her meals. 

So apparently my kitten really likes vegetables! I let her sniff some of the steamed broccoli I made the other day and she loved it! Licking it, biting it, eating it, then begged me for more when she was done. Earlier today I caught her munching on some pieces of green leaf lettuce that she fished from the trash while I was making a salad(don't worry, it was clean).

She has some cat grass but doesn't seem to like it very much, and the enthusiasm she has for the veggies makes me think she's not sick. Her poops are normal and she hasn't vomited or anything. I looked up a few lists of veggies safe for cats but they all say "your cat probably won't like it very much but you can try to sneak it in her food." I was wondering how much I can safely give her per day? 

I know that most of her nutrients should come from meat, but she really went crazy for the veggies. 

Veggies should be more like treats, given occasionally. A very small piece once or twice a week is plenty. I wouldn't give veggies every single day.

Well....plenty of canned cat food has green beans, carrots, and peas in it, although I must admit I've never seen broccoli or lettuce in there .  I'd say if she wants a green bean (or small piece of broccoli)  everyday, it would be ok, just don't let it replace her normal cat food.  (No dis-respect @LTS3)

I know my cats will sometimes "play" with a piece of lettuce of something, but they seldom actually embibe it. 

Yes I would never try to replace meals with a plate full of veggies or anything. I thought I might be able to give her a little more than I would normal treats because veggies are so low in calories/fat so they wouldn't be as bad, but I'll try to keep her consumption low.