In a large mixing bowl combine flour, yeast, sugar and salt. In a small bowl whisk oil and 2/3 cup warm. Pour into flour mixture. Form soft dough. Knead for 8 to 10 minutes in a floured surface. Set aside and the dough rest for 30 minutes.
Heat oil in a large frying pan over medium heat. Add onions and cook for 5 mins. Add mushrooms and cook for 10 mins. Add sour cream and 1 cup of cheese, stir to combine and cook for another 5 minutes until cheese is melted. Set aside.
Roll out the dough until 5mm thick. Cut 18 rounds about 7cm diameter. Line holes of prepared pan with the dough rounds. Fill each muffin with mushroom mixture. Sprinkle with the remaining cheese. Bake for 15 to 20 minutes or until bases are golden and cheese is melted. Serve warm and enjoy.