Place stock, bay leaves, thyme and 250ml water in saucepan over high heat bring to the boil. Stir to break up thyme. Pour into a bowl and set aside.
Heat bacon in a non stick fry pan over medium heat and cook for 4 minutes or until golden. Remove with a slotted spoon and set aside.
Add butter and oil to the pan and stir until the butter melts. Add onion and cook for 3 minutes to soften. Add sliced mushrooms and rice. Cook, stirring for 4 minutes until coated and glossy. Add wine and stir until absorbed. Add stock 1 ½ cups at a time, stirring until absorbed between additions until rice is al dente (this should take about 25 minutes).
To finish, stir in remaining butter and divide between bowls. Return bacon to pan to warm through. Toss through with any remaining thyme leaves from stock bowl and scatter over bowls with Parmesan to serve.