Heat 3 tbsp of oil in a deep skillet over high heat. Add the mushrooms and a pinch of salt and cook, stirring occasionally until they release their liquid and brown.
Add another tbsp of oil and reduce the heat to medium. Add the sliced garlic and allow to brown lightly but don't burn it. Add the fresh spinach and cook until it wilts.
Add the jars of sauce and allow to simmer for 10 minutes, adding a little water if needed. Season with salt and pepper.
Cook the bucatini according to the package. It only needs 3-4 minutes if you use Gusta pasta. Drain and add to the pan with the simmering sauce. Mix well and serve with grated parmesan.