Preheat your oven to 350°F (175°C).
In a large 9x13 inch baking dish, scatter the sliced mushrooms, thinly sliced onion, garlic cloves, and fresh spinach evenly. Then, break the Boursin cheese into chunks and distribute it evenly over the vegetables.
Pour olive oil over the vegetables and season with salt and pepper, red pepper flakes, and Italian seasoning.
Put the baking dish in the oven and bake for 30-40 minutes, until the vegetables are tender, the garlic is roasted, and the cheese has melted into a creamy mixture. About halfway in, gently toss everything together.
While your veggies bake, cook the farfalle pasta in boiling salted water as per the box's instructions. Reserve some pasta water before draining.
After baking, take the dish out of the oven. Stir everything together in the dish and with a fork mash the garlic cloves right in the pan. The cheese should combine with the roasted vegetables to create a creamy sauce.
Mix in the cooked pasta, ensuring it's well coated with the creamy vegetable and cheese mixture. If the sauce seems too thick, add a splash of reserved pasta water to reach the desired consistency.