My 3‑year‑old indoor cat ate a handful of frozen peas that I thawed for a snack, is that okay?

Yes, plain peas are safe for cats. A small amount of thawed or cooked peas can be given as a low‑calorie treat. Make sure they are unseasoned and free of butter, salt, or spices. Watch your cat for any vomiting or diarrhea, and call your vet if anything seems off.