Put the chocolate in a medium bowl. Heat the cream, butter, hot sauce, cayenne and salt in a small saucepan over medium heat until the mixture begins to steam. Pour the cream mixture over the chocolate, and let sit until the chocolate is completely melted, about 10 minutes. Stir until smooth with a rubber spatula or a whisk. (If the chocolate isn't melted, microwave on high in 20-second increments, stirring in between, until just melted.)
Stir in the vanilla. Continue stirring until the chocolate mixture is very smooth and shiny. Transfer it to a shallow dish, like a pie plate, cover and chill until firm, at least 3 hours and up to overnight.
Put the sprinkles on a small plate. Scoop tablespoons of the firm ganache, roll into balls, roll in and place on a parchment-lined baking sheet. Cover with plastic wrap, and refrigerate until firm or until ready to serve, 30 minutes and up to overnight. Roll the truffles in the sprinkles before serving.
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