Preheat your oven to 350°F (175°C).
Grease your bundt pan generously with butter or a non-stick baking spray.
In a saucepan, combine the chopped bittersweet chocolate, butter, and canola oil over medium heat. Stir until melted and smooth, then remove from heat to cool slightly.
In a large mixing bowl, whisk together flour, sugar, cocoa powder, hot chocolate mix, baking soda, and salt until well combined.
In another bowl, whisk together eggs, buttermilk, water, and vanilla extract until smooth.
Pour the melted chocolate mixture into the bowl with the wet ingredients and stir until combined. Gradually add the dry ingredients, mixing until just combined.
Pour the batter into the prepared bundt pan and tap gently on the counter to remove air bubbles.
Bake for 50-60 minutes or until a toothpick inserted in the center comes out clean.
Cool the cake in the pan for 10-15 minutes, then invert onto a cooling rack to cool completely.
Once cooled, dust with powdered sugar or drizzle with chocolate glaze before serving.
