For the whole 8.8-oz package, cook the ravioli according to the package, about 3–4 minutes, and reserve about ¼ cup pasta water. Meanwhile, cut one chicken breast into bite-sized pieces, season with salt, pepper, garlic powder and a little Italian seasoning, and sauté it in 1 tbsp olive oil until cooked through. Remove it, then add 1½ tbsp butter + 2 minced garlic cloves to the same pan. Add 1 cup halved cherry tomatoes and cook 2–3 minutes, then toss in 2 big handfuls of baby spinach until just wilted.
Add the chicken and drained ravioli back to the pan. Splash in a little pasta water and gently toss everything together. Finish with freshly grated Parmesan, black pepper and just a tiny squeeze of lemon. The salty Parmesan and garlic balance the sweetness of the caramelized onion really nicely.
A few other combinations I'd definitely try:
One thing I wouldn't put on these is a heavy marinara. It'll overpower what makes this ravioli good.