Finely chop the chocolate block or use pistoles. The size of the chocolate pieces is key. Make sure the chocolate is in small pieces so that the heat from the boiled cream can melt all of the chocolate.
Place chopped chocolate in a large non-reactive bowl. In a medium saucepan, bring cream, salt, and vanilla bean to a boil. Once mixture has boiled and foamed up, immediately remove the pan from the heat and pour it over the chocolate. Let chocolate and cream mixture sit for 3 minutes. With a wooden spoon, begin stirring small circles in the middle of the bowl. As the smooth mixture begins to form in the middle, slowly expand the size of the circle until the cream and chocolate is fully incorporated. Remove vanilla bean and stir in butter. Cover mixture and let sit until firm.
Fill a piping bag or zip top freezer bag with the truffle mixture and pipe into 1 tablespoon size dollops. Allow dollops to set up until they are firm. Roll dollops into round truffles. Truffles can be coated in powdered sugar, cocoa powder, ground nuts, coconut, etc.
Optional: Add 1-ounce distilled liquor or liqueurs (i.e. brandy, Kirsch, etc.) to butter for additional flavor variations. Distilled liquors or liqueurs add flavor without adding extra sweetness.