1. Preheat oven to 350°F. Spray 13-by-9-inch glass baking dish with nonstick cooking spray; set aside.
2. In small bowl, combine baking mix, milk, and 2 tablespoons of the mayonnaise; pour into prepared dish. Sprinkle sausage evenly over top.
3. In same small bowl, combine remaining ingredients with remaining 2 tablespoons mayonnaise until blended. Pour evenly over sausage. Bake until golden brown, 25 to 30 minutes. Cut into squares.