6 ounces semisweet chocolate pieces, at room temperature
1/2 cup hot coffee
4 egg yolks
2 tablespoons dark rum or 2 tablespoons brandy
1/2 cup butter, cut into smallish pieces and slightly softened
1 Using your electric blender, blend together at high speed the hot coffee and the chocolate pieces (make sure the cover is on) for about 20 seconds or until smooth. (Mr. Price does not indicate what he means by "chocolate pieces" but I think semi-sweet chocolate chips would probably serve well.).
2 Add the egg yolks and dark rum or brandy, cover, and mix at high speed for about 10-15 seconds until the yolks are well incorporated.
3 With the blender running, individually drop in the pieces of butter. From Mr. Price: "If vortex ceases to form, break surface of mixture with a rubber spatula, being careful not to dip too deeply into the blades.".
4 You may needs to use a small rubber spatula to occasionally work the sides of the blender to make sure all the butter is incorporated.
5 When all butter is into the mixture, you should have enough butter cream to fill and frost an 8-inch layer cake. Final note from Mr. Price: "In very warm weather it may be necessary to chill the cream before spreading over a cake.".