In a large bowl, beat sugar and eggs at medium speed with an electric mixer until well combined. Add evaporated milk, water, rum and salt. Beat at low speed until combined. Pour mixture into crust. Sprinkle top of pie with nutmeg and cinnamon. Place pie onto a rimmed baking sheet with a depth of 1/2-inch. Add hot water to baking sheet.
Bake for about 55 minutes, or until a wooden pick inserted near center comes out clean.
Cut into desired sizes and garnish with whipped cream and powdered sugar.