Cook the pasta: Boil the pasta in well-salted water according to the package directions until al dente. Reserve 1 cup of the pasta water, then drain.

Season and sear the chicken: Pat the chicken dry and season with 1/2 teaspoon of the salt and the pepper. Heat the olive oil in a large skillet over medium-high heat and sear the chicken for 6-7 minutes, stirring occasionally, until browned and it reaches 165°F in the center. Transfer to a plate.

Bloom the garlic: Reduce the heat to medium and melt the butter in the same skillet. Add the garlic and cook for 30 seconds until fragrant, scraping up any browned bits.

Build the sauce: Reduce the heat to low and stir in the pesto, heavy cream, remaining 1/2 teaspoon salt, and parmesan until smooth and evenly green.

Combine: Add the drained pasta and seared chicken and toss to coat, loosening the sauce with a splash of the reserved pasta water until it clings to every piece.

Add the tomatoes: Stir in the cherry tomatoes if using, just to warm them through.

Garnish and serve: Top with fresh basil and extra parmesan and serve warm.