Gate the dog out of the kitchen, but only when she's eating. If you want, set her up with her food and then go give the dog a little love while she's eating. And if she wants to feed the dog, let her do it at correct times, and put the food into his bowl. Teach her that dogs eat dog food, not people food. All she has to do is give him chocolate once for him to become very ill, so keep redirecting her tendency to feed the dog, and let her know 'Your food stays on the table. Doggie's food goes in the dish."
And don't let her walk around with her snacks, either. Children should be eating seated at the table, unless there is a planned 'picnic' on the floor. We have a "no walking around with food" practice in our home. That's often how kids end up choking!