Here's one found in HPBooks "More Make-a-MixCookery" byKarine Eliason, etal.

Chocolate Syrup Mix

1 1/3c unsweetened cocoa powder (24 tblsp)
2 1/4 c granulated sugar
1/4 tsp salt
1 1/3 c boiling water
1 1/2 tsp vanilla extract

In heavy saucepan, combine cocoa powder, sugar and salt. Gradually stir in
boiling water. Stir frequently over medium heat until smooth and slightlly
thickened, about 10 mins. Remove from heat. Stir in vanilla. Pour mixture into a
3-cup container with a tight-fitting lid. Attach lid. Label container with date and
contents. Store in refrigerator. Use within 10 to 12 weeks. Makes about 2 2/3 c.

Add 2 tblsp. to a glass of cold milk for a refreshing chocolate drink.

Other recipes included:
Chocolate Chip Ice Cream
Quick Fudge Sauce
Chocolate Ice Cream Soda