Preparation

Make the cake:

• Position a rack in the center of the oven and heat the oven to 325°F. Grease a 10-cup fluted tube pan with the melted butter, using a brush to get into all the nooks and crannies. Lightly flour the pan, tapping out any excess flour.
• In a medium bowl, combine the flour, baking powder, ground ginger, salt, and baking soda. Whisk until well blended and set aside.
• In a stand mixer fitted with a paddle attachment or in a large bowl using a hand-held electric mixer, beat the butter on medium-high speed until smooth, 1 to 2 minutes. Scrape the bowl, add the sugar, brown sugar, and vanilla. Continue beating until very well combined and fluffy, about another 4 minutes. Add the eggs, one at a time, beating well after each addition, and scraping down the bowl as necessary. Add slightly more than half the flour mixture and stir with a rubber spatula until just blended. Add the buttermilk and stir until just blended. Add the crystallized ginger to the remaining flour mixture and use your fingers to break up the clumps of ginger. Add the flour mixture to the batter and stir gently until just blended.
• Scrape the batter into the prepared pan and spread evenly. Bake until a cake tester or toothpick inserted in the center comes out with just a few small, moist crumbs attached, 50 to 55 minutes. Set the pan on a rack and let cool for about 15 minutes. If necessary, run a knife between the cake and the top edge of the pan to loosen the cake. Invert the cake onto a rack, lift off the pan, and allow the cake to cool completely. If using confectioners’ sugar, sift it over the cake just before serving.

Make the whipped cream:

• In a medium bowl, combine the mascarpone, heavy cream, brown sugar, and vanilla. Using an electric mixer, beat on low speed until the ingredients are combined, about 1 minute. Increase the speed to medium high and continue beating until the cream is thick and holds firm peaks, 30 to 90 seconds. Be careful not to overwhip or the cream will become grainy. Serve with the cake.

Make Ahead Tips

Bake the cake up to 5 days ahead but don’t dust with sugar. Wrap the cooled cake in plastic wrap and store at room temperature.