Decadent flavor for now or later... this cake freezes nicely for up to 6 months
Place a rack in the center of the oven and preheat the oven to 350 degrees. Lightly mist a 12-cup bundt pan with vegetable oil spray, then dust with flour. Shake out excess flour. Set the pan aside.
Place the chocolate and water in a small saucepan over low heat. Cook, stirring, until the chocolate is melted, 3 to 4 minutes. Set aside.
Place the cake mix, pudding mix, eggs, buttermilk, oil and vanilla in a large mixing bowl. Fold in the melted chocolate. Blend with an electric mixer on low speed for 1 minute.
Stop the machine and scrape down the sides of the bowl with a rubber spatula. Increase mixer speed to medium and beat 2 to 3 minutes more, scraping the sides down again if needed. The batter should look thick and well combined.
Pour the batter into the prepared pan, smoothing it out with the rubber spatula. Place the pan in the oven.
Bake the cake until it springs back when lightly pressed by your finger and just starts to pull away from the sides of the pan, 45 to 50 minutes. Remove the pan from the oven and place it on a wire rack to cool for 20 minutes. Run a long, sharp knife around the edge of the cake and invert it onto a rack to complete cooling for 20 minutes more.
Frost with chocolate frosting or dust with confectioners' sugar. Store cake, covered with foil or plastic wrap, at room temperature for up to 4 days. Or freeze, wrapped in foil, for up to 6 months. Thaw cake overnight on the counter before serving.
*No buttermilk? Substitute 3/4 tablespoon lemon juice and enough milk to make 3/4 cup.
Source: The Cake Mix Doctor
Please note that some ingredients and brands may not be available in every store.