For people with cats, I usually suggest using baby gates around the house to give the cats "safe zones" if they want and need them. But you have a BC, which may attempt to jump a baby gate, still, it's worth a shot. And maybe it's partly her breed that is the reason she's after the cat a lot. She is a herding dog.

I'm sure with training and correction though, you can at least minimize the behavior.
And I wouldn't just be worried about the dog possibly injuring the cat, but the cat injuring the dog as well. My old dog Harley (a Rottie mix), got swiped by my cat when he was about 4 months old, and an inch higher, he would have lost his eye. It was lucky the claw only ended up cutting his snout. But, he did learn his lesson when it came to cats...LOL. Both of my cats are now declawed due to this, and have been raised with dogs since they were fairly young. And even though I'd never in a million years think my dogs would ever hurt the cats, I still never leave them alone together. You just never know. Just the dogs simply trying to play with the cats can cause an injury.