Position rack in the center of the oven and preheat at 350º. Butter and flour a Bundt cake pan with butter and flour, tap out the excess. Sprinkle caster sugar evenly on bottom of pan.

Whisk flour, baking powder, salt, and baking soda in a medium bowl.

Whisk sour cream and milk in a small bowl.

Sift cocoa into a small bowl. Whisk in honey and 2 tablespoons boiling water until smooth. Cool completely.

Using electric mixer, beat sugar and butter in another medium bowl until light and fluffy, about 3 minutes.

Beat in eggs 1 at the time, occasionally scraping down the sides of the bowl. Beat in vanilla. Add cocoa mixture, stir until smooth, scraping down the bowl occasionally.

Beat in flour mixture alternately with sour cream in 2 additions each until just blended.

Stir in chocolate chips and dried cranberries.

Transfer batter to prepared pan, smooth top.

Bake until tester inserted in the middle comes out clean, about 1 hour. Remove cake from pan and cool.

Sprinkle with powder sugar.