1. Preheat oven to 350°F.
2. Spray a 10-12 cup bundt pan generously with non-stick baking spray. Set aside.
3. In the bowl of a stand mixer fitted with the paddle attachment, beat the butter and sugar together on medium high speed until light and fluffy, about 2 to 3 minutes. Scrape down the sides of the bowl.
4. Add eggs, one at a time until fully incorporated. Scrape down the sides of the bowl.
5. Add the vanilla and mix until just combined.
6. In a medium bowl, whisk together flour, cocoa powder, baking powder, baking soda, salt, nutmeg and cardamom. With mixer on low speed, slowly add the flour mixture to the butter mixture alternating with the buttermilk and sour cream. Mix until just barely combined with a few streaks of flour remaining. Do not over mix.
7. Remove the bowl from the mixer and add the hot water. Stir with with a rubber spatula until the batter is smooth.
8. Transfer the batter into the prepared bundt pan. Tap pan firmly on the countertop 3 times to release any air bubbles.
9. Bake for 45-50 minutes or until a toothpick inserted into the center of the cake comes out clean or with a few crumbs remaining. If the top of the cake is browning too quickly, loosely cover the top with aluminum foil for the last 10 minutes of baking.
10. Remove the cake from the oven and cool on a wire rack for exactly 10 minutes. After 10 minutes, use a cooling rack or cake platter to invert the cake. Flip the cake once more to expose the rough bottom face up. Cool completely before adding the glaze.

For Donut Glaze

1. In a medium bowl whisk together powdered sugar, milk and vanilla until smooth and pourable. If glaze is too thin, add more powdered sugar. If too thick, add more milk.
2. Drizzle the glaze over the cooled cake, being sure to drench the top allow the glaze to drip over the sides of the cake. The glaze will harden as it sits. For best results, allow to rest for 10 to 15 minutes before slicing.