1. Cook ravioli in microwave according to package directions.

2. While ravioli cooks, heat oil in a large nonstick skillet over medium-high heat. Add mushrooms and onion; sauté 3 to 4 minutes or until richly browned. Combine flour and next 4 ingredients in a small bowl, stirring until smooth. Add to pan, stirring well. Cook over medium-low heat 2 minutes or until mixture thickens slightly.

3. Divide cooked ravioli evenly among 4 shallow bowls or plates; spoon mushroom mixture evenly over ravioli. Sprinkle cheese evenly over each serving; garnish with basil, if desired.