6 year old daughter sneaking food

My 6 year old daughter has been coming out of her room after bedtime and sneaking excessive amounts of food from the kitchen.
We allow our kids to eat whatever they want basically. We are definitely more an ingredient household, but occasionally buy cookies or have leftover birthday cake, baking supply’s (sprinkles, chocolate chips etc) or similar things. Always fruit available, always asking my kids (6,5,4,3) what they want to eat for meals/snacks, include them in baking and cooking constantly. At least everyday I make the kids some version of ‘healthier’ cookies, cookie dough, brownies, ice cream, I have a huge sweet tooth, but prefer only whole foods, and they see those things as treats.
Lately my daughter has been coming out after bedtime and taking and eating full large size bags of chocolate chips, whole containers of sprinkles, recently ate 2lbs of peaches in one night, taking 4-5 oranges, apples, or bananas per night, sleeves of cookies, containers of leftover cake, the list goes on.
What do I do? My husband and I have had so many conversations about how we can’t afford for her to be eating that much, especially since she usually has 3-4 helpings of food for breakfast, lunch, and dinner, I know she’s not starving as she also has snacks throughout the day. we talk about sharing and it’s not fair that she’s eating all the snacks and her siblings are getting nothing. And basically how it’s not good for your body to be eating that much of something at one time. She is very active and no where near overweight. We do suspect she has ADHD and have been talking with her doctor about this.
What can we do to help or stop this behaviour? I’m at a loss. Locking her room at night feels wrong, telling her she can’t eat food feels wrong, how do I get her to understand it’s not ok?