In a 4-quart Dutch oven combine the chocolates, half-and-half or light cream, and sugar.
Bring to boiling; reduce heat.
Simmer mixture, uncovered, over low heat about 2 minutes or until mixture is creamy, stirring frequently.
Remove from heat; stir in the vanilla.
Pour the hot sauce into 7 or 8 hot, clean half-pint jars or 16 (4-ounce) jars, leaving a 1/2-inch headspace.
Place metal lids on jars.
Screw metal bands onto jars following manufacturer's directions.
Store chocolate sauce in the refrigerator for up to 3 weeks.
(The sauce must be stored in the refrigerator after placing in jars. Even though the hot sauce may cause the lids on the jars to seal, this is not a secure canning seal. Do not store at room temperature.) Serve sauce warm* over ice cream, eclairs, or fresh berries.
Makes eight 1/2-pint or sixteen 1/2-cup jars (128, 1-tablespoon servings)*Note: To reheat, place 1/2 cup sauce in a 1-cup glass measure.
Microwave, uncovered, on 100% power (high) for 1-1/2 to 2 minutes or until heated through, stirring once.
Or, place in a small saucepan.
Cook and stir over medium heat about 5 minutes or until heated through.