01 - Preheat oven to 350°F. Generously grease and flour a 10-cup Bundt pan, ensuring every crevice is 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 until fully incorporated. Mix in the vanilla extract.
05 - Alternately add the sifted dry ingredients and the 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 thickest part of the cake comes out clean.
08 - Let the cake cool in the pan for 15 minutes, then carefully invert onto a wire rack to cool completely before glazing.
09 - In a small saucepan, heat the heavy cream until just steaming (do not boil). Pour the hot cream 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 cranberries with water, then roll them in granulated sugar until evenly coated. Let dry on a wire rack. Arrange the sugared cranberries and rosemary sprigs around the top of the cake to resemble a holiday wreath. Dust lightly with powdered sugar for a snowy finish.