Cut the chicken into 1 inch pieces and pat them dry. Season with the salt and pepper. Mince the garlic and set it aside.

Heat the olive oil in a large pot or deep skillet over medium-high heat. Add the chicken in a single layer and cook without moving it for 3 minutes, then stir and cook 2 to 3 minutes more, until browned and 165°F inside. Move the chicken to a plate.

Add the garlic to the same pot and stir for 30 seconds. Pour in the broth and water, scrape up the browned bits, and bring it to a boil.

Add the pasta, drop the heat to a steady simmer, and cook uncovered for 9 to 11 minutes, stirring every couple of minutes so nothing sticks. The pasta is done when it is tender and most of the liquid has been absorbed, with a few spoonfuls of starchy liquid left in the bottom.

Turn off the heat. Add the spinach in handfuls and stir until it wilts, about 1 minute.

Stir in the pesto, Greek yogurt, lemon juice, and the cooked chicken with any juices from the plate. Keep the heat off so the yogurt stays smooth.

Taste and add a pinch more pepper if you like. Divide into 4 bowls and top with the parmesan. Serve right away.