Heat oven to 400°F. In 10-inch nonstick skillet, heat 3 teaspoons of the oil over medium heat. Add onion; cook uncovered 10 to 15 minutes, stirring frequently, or until tender and golden brown.
Remove onion from skillet; set aside. Cook sausage in same skillet over medium-high heat about 5 minutes, stirring occasionally, or until lightly browned.
Brush 1 teaspoon of the oil in bottom of 15x10-inch pan with sides. Unroll pizza dough in pan; press dough to fit pan. In small bowl, mix cream cheese and maple syrup until well blended. Spread evenly over pizza dough. Top cream cheese layer evenly with onion and sausage. Sprinkle with cheese.
In medium bowl, toss sliced sweet potato with remaining 1 teaspoon oil, nutmeg and thyme. Evenly distribute sweet potato slices over pizza. Sprinkle with salt and pepper.
Bake 18 to 25 minutes or until crust is golden brown, cheese is melted, and sweet potato slices are tender. To serve, cut into 8 squares.