01 - Preheat oven to 350°F. Generously grease and flour a 10-cup Bundt pan, ensuring every crevice is coated to prevent sticking.
02 - Sift together the all-purpose flour, cocoa powder, baking powder, baking soda, and salt in a medium bowl. Set aside.
03 - In a large mixing bowl, beat the unsalted butter and granulated sugar together using an electric mixer on medium-high speed until pale, light, and fluffy, approximately 3 minutes.
04 - Add the eggs one at a time, beating thoroughly after each addition until fully incorporated. Blend in the vanilla extract.
05 - Alternately add the sifted dry ingredient mixture and the buttermilk to the butter mixture in three additions, beginning and ending with the dry ingredients. Fold gently until just combined — avoid overmixing to keep the crumb tender.
06 - Pour the batter evenly into the prepared Bundt pan and smooth the surface with a spatula. Bake for 45–50 minutes, or until a wooden skewer inserted into the center emerges clean.
07 - Let the cake rest in the pan for 15 minutes, then carefully invert onto a wire cooling rack. Allow to cool completely before glazing.
08 - In a small saucepan, heat the heavy cream over medium-low until just steaming — do not boil. Pour the hot cream over the semisweet chocolate chips and butter in a heatproof bowl. Let stand for 2 minutes, then whisk until silky and smooth.
09 - Drizzle the warm chocolate glaze over the fully cooled cake, allowing it to flow naturally down the sides for an elegant drip effect.
10 - Lightly dampen the fresh cranberries with water, then roll them in granulated sugar until well coated. Let dry on a wire rack. Arrange the sugared cranberries and rosemary sprigs around the top of the cake to resemble a festive holiday wreath. Finish with a light dusting of powdered sugar for a snowy effect.