Cook pasta al dente in boiling, salted water according to package instructions.

Add 1 tablespoon olive oil in a large sauté pan over medium-high heat. Add onions and sauté for 5 minutes, stirring occasionally. Add the remaining 2 tablespoons of olive oil, garlic and mushrooms, and stir to combine. Continue cooking for an additional 5-7 minutes, until the mushrooms are cooked and tender. Add the white wine, and deglaze the pan by using a wooden spoon to scrape the brown bits off the bottom of the pan. Let the sauce simmer for 5 minutes.

Meanwhile, in a separate bowl, whisk together the vegetable stock, Worcestershire and flour until smooth. Pour the vegetable stock mixture into the pan with the mushroom, along with the thyme, and stir to combine. Let the mixture simmer for an additional 5 minutes.

Add the yogurt and mix evenly into the sauce. Taste, and season with salt and pepper as needed.

Serve immediately with pasta.