Brush a Bundt pan with soft butter, making sure to cover all little nooks and crannies. Pour in some sugar, tilt & turn Bundt pan to cover with sugar evenly. Pour out rest of sugar. Set aside.
Whisk butter with vanilla and sugar light and pale, adding eggs one at a time.
Scale and combine cake flour, baking soda, cornstarch and salt. Dry stir to blend well.
Working in three stages, incorporate flour blend into whipped butter base.
Naughty Cocoa Swirl: Combine warmed milk with Naughty Cocoa Mix & Canola oil. Stir to a smooth paste. Mix this Cocoa paste with ¼ of the above cake batter.
Take the remaining ¾ of the cake batter and transfer to prepare Bundt pan. (add chopped dates and white chocolate Chips at this stage if using)
Now scoop Naughty Cocoa batter on top of cake base. Using the handle of a cooking spoon or a chop stick, swirl in Naughty cocoa batter.
Push Bundt cake into the center of the oven at 350F/160C and bake for approx. 35-40min or until a cake tester (or wooden skewer) inserted in the center of Bundt cake come out clean with moist crumbs.
Remove Bundt cake from the oven and allow to cool off for 10minutes in its tin, then unmold cake and cool off on a wire rack.