In large pot, bring water to boil on high heat. Add orzo; stir. Reduce heat to medium-high and cook pasta, uncovered, for 10 minutes.
Drain pasta through colander and rinse under cold running water. Shake off excess water; set aside.
Preheat oven to 350°F. Butter bottom and sides of 8x8x3-inch baking dish with softened butter.
In large mixing bowl, whisk together mascarpone, egg yolks, sugar, salt and vanilla. Once cheese mixture is smooth and completely free of lumps, whisk in milk. Fold in cooked pasta; set aside.
With electric mixer, beat egg whites until stiff peaks form. Fold beaten egg whites into custard mixture in 3 batches.
Pour mixture into the prepared pan. Place oven rack in middle of oven and bake 35-40 minutes or until top is brown, edges are firm, and center jiggles only slightly when pan is shaken. Let baked soufflé cool down to slightly warmer than room temperature before serving.
To serve, spoon some coconut cream onto plate, place square of the soufflé right in pool of coconut cream, and garnish with diced mango.