Toss gnocchi and mushrooms in olive oil then sauté, stirring frequently, for 5 min. Melt butter in separate small saucepan then add pressed garlic and cook 20 seconds over medium heat. Add flour and stir for a minute. Add milk and stir until smooth paste forms, then remove from heat, add cream and parmesan. Return to heat briefly to melt all the cheese, stirring vigorously until texture is smooth. Mix gnocchi, cream mixture, stock and thyme in slow cooker and cook on slow for 2 hours.