Heat the olive oil in a skillet over medium-high heat on the stove.

Add the chicken to the skillet, and saute until almost cooked through.

Put the mushrooms in the skillet, and saute until the chicken is cooked completely and the mushrooms are tender.

Toss in the spinach and saute until it is wilted. Add salt and pepper to taste.

Remove the mixture from the skillet.

Reduce the heat to medium, and add the butter and garlic to the skillet. Saute for 30 seconds.

Pour the heavy whipping cream and pumpkin puree into the skillet. Whisk to combine completely.

Continue to cook the sauce down until it begins to thicken.

Mix in the grated parmesan.

Add the chicken and veggies to the skillet with the sauce, and toss to coat before serving.