Preheat oven to 180°C Chop onion finely. Slice button mushrooms. Heat olive oil in a non-stick pan, add onion and mushrooms and sauté. Crush garlic cloves and add. Add salt and cook till dry and lightly browned. Transfer mushrooms into a bowl and let them cool. Slice bread thinly and toast in the preheated oven till crisp. Remove from oven and arrange on a baking tray.
Add cream and cheese to mushrooms and mix well. Spread this mixture over the toasts generously. Place tray in preheated oven and bake till cheese melts. Serve hot.