My (27M) girlfriend (26F) loves cooking for me but she doesn't know how

A little bit of backstory: I met my girlfriend at a cooking competition a few years back. She was pretty upset when she didn't win so I offered to take her out to diner and one thing led to another, now we're living together in my apartment.
Now, to say that my girlfriend LOVES cooking for me is the understatement of the week. She will make a whole day out of going out to get ingredients and she even asks me what I want to come home to. She spend her days off cooking; she loves it. Shes always wanted to be a chef but never had the means to go to culinary school. When I get home, there's always a very well-set table with candles and the works with a hot plate of numerous different foods she knows I like. She'll always sit down with me and ask me about my day with the loveliest smile I've ever seen. She doesn't eat much plus she's a fast eater so she always finishes well before I do but she'll stay at the table to talk to me and keep me company. Recently, she read this women's health blog where she read that people waste too much money eating out on a regular basis so now she makes it a point to cook meals for both herself and I much more frequently. She packs a lunch for me to take to work with a little note that always says she loves me, have a nice day, etc.
Now, I don't think I need to express how grateful I am to have such a wonderful girl in my life and I know that what she does for me is out of love and care. I still get butterflies when I think about how her putting in all this effort speaks about how much she loves and appreciates me. I really do. But theres only one problem:
The food is terrible
I'm not just talking about tasting a bit off or a little too much salt. I'm talking about borderline inedible. I hate to admit this but I have even gagged sometimes when I eat. It is torture, I do not enjoy eating at all. I have tried everything I can think of to change her cooking a bit.
I tried cooking for both of us, she got upset because she loves cooking for me and doesn't want me to worry about having to do any work when it comes to food.
I tried cooking WITH her... same story
I took her to a cooking class where we could both learn to cook delicious food. What she made that day in the class tasted delicious! When we got home, she admitted she did not like what she made in class at all and that she would continue to cook in her style.
I have tried to get her to follow recipes, she always ends up putting her own "spin" on things and it never tastes good. If I insists she follows it to the letter, she accuses me of not liking her cooking, not appreciating her and it always ends in her crying.
I will admit I am ashamed of this one but I tried to eat out before I got home and blame it on overtime. When I got home, she gave me a huge kiss and told me to let her "make me happy" (AKA cook) next time. She even offered to drive over and drop off my food at work.
I tried suggesting that I wanted to show her how much I appreciated her cooking for me by suggesting I cook some dishes she likes for her. Her response was that she enjoys cooking because she does it for me not because she likes food all that much.
She tells me one of the reasons she loves to cook for me is because, I'm the only person who enjoys her food. Nobody else will eat her food. There have been times where I had to eat entires bowls of food over the course of weeks because she made it and it went virtually untouched at a party.
Now there have been a couple of times where she suspected I didn't like what she made. she really took offense to that and cried. Dating.mobi, I don't have the heart to break hers; I don't have the heart to tell her the truth. I just can't bring myself to say it, that smile and twinkle in her eyes just won't let me. What can I do?
TL;DR: MY girlfriend adores cooking for me and is an absolute darling about it, but her cooking is terrible.


Source.

That's lovable dedication... wish I should be also such enthusiastic... I always wanted to do this.