They are such a lavish treat that I couldn’t believe they came together with so few ingredients, just give yourself plenty of time for the chocolate ganache to set.
In a small saucepan over medium heat, bring the cream to a boil. Put half the chocolate into a large mixing bowl and immediately pour the heated cream over the top. Stir constantly until the mixture is smooth. Stir in the champagne and salt.
Refrigerate until the chocolate mixture is firm enough to roll into balls, about 2 hours or up to overnight. Use a melon baller or rounded tablespoon to scoop and roll 1-inch balls.
Transfer to a parchment paper-lined baking sheet and continue with the remaining chocolate mixture. Cover with plastic wrap and refrigerate 30 minutes.
Melt the remaining chocolate using the double boiler method. Bring a saucepan of water to a boil over medium heat and set a heatproof metal bowl over the top. Add the remaining chocolate and cognac and stir until completely melted and smooth, about 3 minutes.
Roll the chilled truffles in the melted chocolate and return to the parchment paper-lined baking sheet and top with the gold sprinkles. Refrigerate until the chocolate exterior is solid, at least 1 hour and up to 3 days before serving.