Begin by bringing a large pot of salted water to a boil. Add the pasta and cook according to the package instructions until al dente. This usually takes around 10 minutes, depending on the type of pasta used.
Reserve about ¼ – ½ cup of the pasta cooking water, drain the pasta and set it aside.
In a large skillet, heat the olive oil or butter over medium heat. Add the finely chopped garlic, thyme, and sauté for about 20 – 30 seconds. Be careful not to burn the garlic, as it can turn bitter.
Add the sliced mushrooms to the skillet. Season with salt. Cook stirring occasionally, until the mushrooms are golden brown and have released their moisture.
Add red wine vinegar, oregano, and ¼ cup of stock or reserved pasta water. Taste and adjust the seasoning with more salt and pepper if needed. Stir the sauce and increase the gas flame to high.
Add the cooked pasta and baby spinach to the skillet.
Toss everything together until the pasta is well coated with the sauce and spinach leaves softened. This could be more like a stir frying step.
Once the pasta is well coated and the sauce is creamy, remove the skillet from the heat.
Garnish with freshly chopped parsley or drizzle of chilli oil. Serve warm with toasted garlic bread.