To prepare topping, combine first 8 ingredients. Cover and let stand at room temperature.
To prepare risotto, melt butter in a 6-quart pressure cooker over medium heat. Add onion; cook 2 minutes, stirring frequently. Add rice and garlic; cook 2 minutes, stirring constantly. Add wine; cook 1 minute or until liquid is absorbed, stirring frequently. Stir in broth, 1/2 teaspoon salt, 1/4 teaspoon black pepper, and nutmeg. Close lid securely, and bring to high pressure over high heat. Adjust heat to medium or level needed to maintain high pressure; cook 6 minutes. Remove from heat; place cooker under cold running water. Remove lid. Stir in cheese, rind, juice, and basil. Top with tomato topping.