Preheat your convection oven to 350°F (175°C).

In a large mixing bowl, cream together the granulated sugar, softened unsalted butter, and vanilla extract using an electric mixer until light and fluffy, about 3-5 minutes.

Add the large eggs one at a time, beating well after each addition until the mixture is smooth.

Whisk together the cake flour, baking cocoa powder, baking soda, salt, and instant chocolate pudding mix in a separate bowl.

Slowly alternate adding the buttermilk and the dry ingredients to the creamed mixture, mixing until just combined.

Gently fold in the semi-sweet chocolate chips.

Grease a tube pan, pour the batter into the pan, and bake for 60-70 minutes, until a cake tester comes out clean.

Remove the cake from the oven and let cool completely in the pan on a wire rack for about 15-20 minutes.

Melt together water, butter, and vanilla in a saucepan, whisk in cocoa powder, then gradually add powdered sugar and heavy cream to achieve desired icing consistency.

Once the cake is cool, spread icing evenly over the cake.