Bring a large pot of salted water to a boil. Add the pasta and cook for about 2 minutes less than the package directions for al dente. Drain and set aside.

In a large skillet, heat a drizzle of olive oil over medium-high heat. Add the chicken breast pieces, seasoning them lightly with salt and pepper. Sear until golden on the outside but not fully cooked through.

Remove the chicken and add the butter to the same skillet. Toss in the diced onion and minced garlic. Sauté until the onion is translucent.

Lower the heat and stir in the heavy cream and the pesto sauce. Whisk gently until the mixture is a pale forest green and starts to simmer. Stir in half of the parmesan cheese until melted.

In a large 9x13 inch baking dish, toss the undercooked pasta, the seared chicken, and the cherry tomatoes together. Pour the luscious pesto cream sauce over everything, ensuring every nook and cranny of the pasta is coated.

Sprinkle the mozzarella cheese and the remaining parmesan over the top. Add a pinch of oregano.

Place the dish in the oven and bake for 20 to 25 minutes. You are looking for the edges to be bubbling and the cheese to have developed those beautiful, toasted spots of gold.