Heat the oven to 375°F/190°C convection.
Peel the sweet potato and cut it into ½-inch rounds. Arrange on a parchment-lined sheet pan, brush with olive oil, and season with coarse salt. Roast until tender and lightly caramelized, about 20 minutes. Cool slightly.
Combine tomatoes, onion, parsley, lemon juice, and salt to make the topping.
Spread the cream cheese evenly over the sweet potato rounds. Spoon the tomato mixture on top and finish with a drizzle of balsamic reduction, if using. Serve immediately.