Heat the olive oil in a large skillet over medium-high heat. Season the diced chicken breast with half of the salt and pepper, then sear until golden and cooked through. Remove the chicken from the pan and set aside.
In the same skillet, add the sliced cremini mushrooms and sauté until they release their moisture and develop a deep golden-brown color.
Add the minced shallot and garlic to the skillet with the mushrooms, cooking for 1 minute until fragrant.
Stir in the Arborio rice, toasting the grains for about 2 minutes until the edges become slightly translucent.
Reduce the heat to medium. Begin adding the chicken broth 0.25 cup at a time, stirring frequently and allowing the liquid to be fully absorbed before adding the next portion.
Continue the process until the rice is tender and has reached a naturally creamy consistency.
Fold the cooked chicken back into the skillet along with the parmesan cheese, fresh thyme, and the remaining salt and pepper.
Stir until the cheese is melted and the risotto is rich and velvety, then serve immediately.