- Combine flour, sugar and salt in food processor.
- Add butter and process until mixtures resembles coarse meal.
- Whisk egg and water in a small bowl.
- Mix in enough of egg mixture to bind dough.
- Gather dough into a ball, wrap in plastic and let stand 1 hour.
- Preheat oven to 450°F and position rack in center.
- Cook sugar with 2 tbsp water over medium heat, stirring until sugar dissolves.
- Increase heat and boil without stirring until syrup turns deep golden brown.
- Whisk in butter.
- Immediately pour into 9" glass pie dish.
- Arrange mango evenly in dish.
- Roll dough out on lightly floured surface.
- Place over fruit.
- Trim edges and press to dish to seal.
- Bake until golden brown, about 40 minutes.
- Place heatproof plate over pie dish.
- Using oven mitts, quickly invert tart onto plate.
- Serve warm with whipped cream.