In a large frying pan with canola oil, saute the sliced mushrooms. When moisture just starts to appear and the mushrooms are starting to brown, flip them over. When lightly browned, remove from heat and set aside. Continue until all the mushrooms are cooked adding more oil as necessary.
in a large pot over medium heat, melt the butter and cook the diced onions until soft. Add garlic, salt and pepper cook for another minute while stirring.Add the flour while continuing to stir and cook for another 1-2 minutes.
Slowly add the chicken broth, stirring until the mixture thickens and just starts to bubble.
Add ¾ of the mushrooms, turn the heat to low and simmer for 5 minutes. Remove from heat and blend until smooth.
Return the blended soup to a clean pot. Chop the remainder of the mushrooms and add to the soup. Finish with cream, stir and reheat until hot. Serve in bowls with freshly ground pepper.