01 - Preheat oven to 350°F. Grease and flour a 10-cup Bundt pan thoroughly, ensuring all crevices are coated to prevent sticking.
02 - In a medium bowl, sift together the all-purpose flour, cocoa powder, baking powder, baking soda, and salt. Set aside.
03 - In a large bowl, beat the room-temperature butter and granulated sugar with an electric mixer until light and fluffy, approximately 3 minutes.
04 - Add the eggs one at a time, beating well after each addition. Stir in the vanilla extract until evenly distributed.
05 - Alternately add the sifted flour mixture and buttermilk to the butter mixture, beginning and ending with the dry ingredients. Mix until just combined—do not overmix to keep the crumb tender.
06 - Pour the batter evenly into the prepared Bundt pan and smooth the top with a spatula.
07 - Bake for 45–50 minutes, or until a wooden skewer inserted into the center comes out clean.
08 - Allow the cake to cool in the pan for 15 minutes, then invert onto a wire rack and let cool completely before glazing.
09 - In a small saucepan, heat the heavy cream until just steaming. Pour over the chocolate chips and butter in a heatproof bowl. Let sit for 2 minutes, then whisk until smooth and glossy.
10 - Drizzle the chocolate glaze over the completely cooled cake, allowing it to flow naturally down the sides.
11 - Lightly dampen the fresh cranberries with water, then toss in granulated sugar to coat. Let dry on a wire rack. Arrange the sugared cranberries and rosemary sprigs on top of the glazed cake to resemble a Christmas wreath. Dust lightly with powdered sugar for a snowy finish.