Cook the pasta. Bring a large pot of salted water to a boil. Add the pasta and cook the pasta until al dente.
Remove 1.5 cups of starchy pasta water from the pot before straining the pasta.
Rinse the pasta with cold water so it stops cooking and set aside for later.
Prepare the chicken. Lay the chicken down on a flat surface and cover it with plastic wrap. Pound the chicken with a meat tenderizer until the chicken is all one equal thickness, about 1-inch thick.
Cut the chicken into ½ inch strips and place the chicken into a bowl. Set aside.
Prepare the dry rub for the chicken. Add the flour, garlic powder, dried thyme, ½ teaspoon salt, and ground pepper to a bowl and mix until well combined. Sprinkle the dry rub over the chicken strips and toss the chicken with the dry rub until the chicken strips are coated.
Next, heat a large skillet or cast iron pan with sides over medium/high heat. Add 2 tablespoons of olive oil to the skillet. Be sure the olive oil coats the bottom of the pan.
When the olive oil is fragrant, add one layer of the chicken strips to the pan. You may have to cook the chicken in 2 batches depending on how big your pan is.
Cook the chicken for 2-3 minutes on each side or until the chicken is golden brown and the internal temperature of the chicken reaches 165ºF. Remove the chicken from the pan and set aside.
Turn the heat to medium and deglaze the pan with white wine. Use a wood utensil to scrape the bottom of the pan to loosen all the brown bits from the pan (this is where the flavor is).
Add the white onion and season with ¼ teaspoon salt. Sauté for about 2 minutes.
Drizzle the last 1 tablespoon of olive oil into the pan and then add the mushrooms. Toss the mushrooms with the onion and olive oil. Turn the heat to medium/high and sauté for 3 minutes.
Add the garlic and ¼ cup of the beef broth to the mushrooms. Sauté the mushrooms for an additional 2-3 minutes or until the mushrooms begin to brown slightly.
Next, add the sun dried tomatoes and the remaining salt to the pan and toss.
Add ½ cup of the starchy pasta water and remaining broth to the pan and then whisk in the tomato paste. Bring the mixture to a gentle boil. The sauce will start to thicken.
Once the sauce has thickened, remove the pan from the heat and slowly whisk in the heavy cream until combined.
Return the pan to the heat and heat the sauce over medium heat.
Add the chicken and pasta to the sauce and toss all the ingredients together until the pasta and chicken are coated.
The pasta will absorb most of the sauce and it will be absolutely delicious, but if you want it saucier, add more starchy pasta water by the tablespoon.
Top the pasta with a generous amount of grated parmesan and fresh thyme.