Preheat oven to 350°F. Lightly grease/spray an 8" or 9" square baking dish. You will also need a larger dish or pan to fill with water and set the baking dish into.
Combine the Grape-Nuts® and milk in a mixing bowl. Let sit for 5 minutes to soften up the cereal.
Whisk together sugar, eggs, vanilla & salt.
Combine egg mixture with the cereal mixture.
Pour into baking dish. Sprinkle top generously with cinnamon & nutmeg.
Place baking dish into larger pan and then pour hot water into the larger pan around your custard baking dish. (Water bath/bain marie)
Bake for 45 - 50 minutes or until knife inserted in center comes out clean.
Remove dish from larger pan and cool. This is good warm and wonderful chilled. You decide which is better.
I serve this sprinkled with additional cinnamon or cocoa powder and whipped cream.