Stir coconut into boiling water in a large bowl. Let sit for 15 minutes, then strain through cheesecloth, squeezing out all of the liquid to yield 3 cups.
Stir together the cornstarch, sugar, nutmeg, and salt. Bring the coconut milk to a simmer in a saucepan over medium-high heat. Whisk in the sugar mixture, and cook until thickened, stirring constantly. When very thick, remove from heat ,and stir in vanilla. Pour into an 8x8-inch pan, and cover with plastic wrap. Refrigerate until set.
