Prepare the Ice Cream: Bring 1 1/2 cups water to a simmer in bottom pan of a double boiler over medium. Combine milk, cream, brown sugar, salt, eggs, and remaining 1 1/2 cups water in top of double boiler, and cook, whisking constantly, until sugar dissolves, about 15 minutes. Continue to cook, stirring often, until mixture thickens and thinly coats the back of a wooden spoon, about 15 minutes. Add butter and vanilla, and cook, stirring constantly, until butter melts, about 2 minutes. Transfer to a medium bowl; cover and chill until cold, about 2 hours.

Pour chilled mixture into the frozen freezer bowl of a 1 1/2-quart electric ice-cream maker, add chopped pecans, and proceed according to manufacturer’s instructions. (Instructions and time may vary.) Transfer Ice Cream to a freezer-safe container; cover and freeze until firm, about 1 hour.

Prepare the Praline Sundae Topping: Combine sugar, corn syrup, and butter in a medium saucepan over medium. Bring to a boil, and cook, stirring constantly, 2 minutes. Remove from heat, and cool slightly, about 15 minutes.

Whisk in evaporated milk until smooth. Stir in pecans and salt. Cool to room temperature, about 20 minutes.

Transfer topping to an airtight container, and chill until thickened, about 30 minutes. Serve over Ice Cream.