In a large saucepan, heat butter and oil on medium heat until they are melted. Sauté onion until softened, about 2 to 3 minutes. Sauté garlic for about one minute, or until fragrant.
Cook for 5 minutes. Add mushrooms and 2 teaspoons of thyme. Allow to simmer for 3 minutes.
Mix flour and mushrooms together, then cook for 2 minutes. Mix in the stock and bring to boil. Reduce heat to low heat and season the mixture with salt, pepper, and crumbled Bouillon cubes.
Allow to simmer covered for about 10-15 minutes, stirring occasionally, until the mixture thickens.
Reduce heat to low and stir in cream, half-and-half or cream. Allow to simmer gently (do NOT boil). Salt and pepper can be adjusted to suit your tastes.
Add parsley and the remaining thyme. Serve warm.