10 ounces (283 g) chopped semisweet or bittersweet chocolate (see note)
⅓ cup milk (preferably not skim milk)
⅓ cup heavy cream
1 teaspoon vanilla extract (see note)
Dipping options: strawberries, bananas, small rice krispie squares, vanilla cookies, etc.

In a saucepan or stovetop-proof fondue pot, combine the chocolate, milk and cream, and heat on low, stirring often, until the chocolate is completely melted and the mixture is glossy and smooth. Don't let it come to a boil.
Once melted, stir in the vanilla extract. The fondue will likely be fairly thick. If a thinner consistency is desired, whisk in heavy cream or milk a little bit at a time until you reach the ideal consistency.
Pour the mixture into a fondue pot or small slow cooker to keep warm while serving.
Serve with dippers of your choice like: strawberries, bananas, small rice krispie squares, vanilla cookies, etc.
Leftover fondue keeps well in the refrigerator. Warm over low heat, stirring often, to reheat.