Add oil to large skillet over medium heat. Sweat garlic over medium heat until golden. Add mushrooms, salt to taste and sweat over medium heat until mushrooms begin to give up mositure. Add thyme, increase heat and cook until mushrooms are very tender, golden browned and no more moisture is being released. Add tomatoes and saute for a few minutes to integrate flavors. Remove from heat and add hot pasta and 1/4 cup of pasta water to pan along with spinach. Toss to combine, allowing spinach to wilt slightly.