To make the ice cream base: Stir the gelatin into 1/2 cup of cold water in a small bowl; Set the mixture aside (this will bloom into a semi-solid state).
Heat 2 cups of the milk in a saucepan over medium-low heat, stirring occasionally. When the milk begins to steam remove it from the heat. And stir in the gelatin. Stir until the gelatin is fully dissolved.
Put the malted milk powder into a blender. Add 2 cups of the cold milk. Blend well, stopping to scrape down the sides with a spatula. (If there's no blender handy, just beat the malted milk well into the milk until there are no lumps).
Pour the malted milk mixture into the ice cream maker. Add the heavy cream and stir. Stirring constantly, mix in the hot milk and gelatin mixture. Add the remaining milk, sugar, vanilla, and salt and stir until the sugar dissolves.
To freeze the ice cream: Assemble the dasher, position the can lid, put the can in the tub and secure the crank assembly. Turn the crank to make sure everything is put together correctly.
Find the little hole in the side of the tub near the top of the can. Make sure that the hole is open. Drop about 2 cups of crushed ice into the tub. Sprinkle the ice with 1/2 cup rock salt, evenly covering it. Repeat this process. Now someone should begin turning the crank, which remain in motion until the ice cream is frozen.
Continue to add ice and salt in the proportion above until you have reached the top level of the can and continue cranking. In about 20 minutes the crank will become very difficult to turn. This indicates that the ice cream is done.
Remove the crank assembly. Pull the can up a bit in the tub. Wipe the ice and salt from the lid and the top of the can. Remove the lid. Pull up the dasher and scrape it off with a rubber spatula. Most people dig in right at this point and enjoy the ice cream even though it is still a little soft. Others like to remove the can and put it in a freezer (or put the ice cream into smaller containers) and harden the ice cream for a few hours before eating.
Cook's Note: To make delicious vanilla ice cream, simply omit the malted milk powder.