To make an alcohol-free variation of this cake: Omit the rum and vanilla extract.
To make the pound cake:
Preheat oven to 350 degrees F (conventional) or 335 degrees F (convection). Set the rack in the middle of the oven. For Crunchy Feet, set racks in the upper-middle and lower-middle positions.
Set out the ingredients and equipment. Sift the flour directly into a bowl on a scale for accurate measuring. Measure the other dry ingredients into a separate mixing bowl, add the flour, and whisk for 10 seconds to blend. Set aside. Measure the liquid ingredients into a separate bowl, whisk to combine, and set aside. Measure the butter and sugar into separate bowls and set aside. Crack the eggs and yolks into two separate bowls and set aside.
In the bowl of a standing mixer fitted with the paddle attachment, cream together the butter and sugar on the lowest speed for 3 minutes. This is a very dense cake so aerating well is important.
With the mixer still on the lowest speed, add the eggs one at a time followed by the yolks, fully incorporating after each addition. Stop the mixture and scrape the sides of the bowl.
Add the dry ingredient mixture alternately with the liquid mixture in 3 to 5 additions each, beginning and ending with the dry mixture. Move swiftly through this step to avoid overworking the batter. Don’t wait for the dry or liquid mixtures to be fully incorporated before adding the next. This step should take a total of about 60 seconds.
Stop the mixer and scrape the sides of the bowl all the way down. Don’t miss the clumps of ingredients hiding on the bottom of the bowl. Mix on medium speed for 15 to 20 seconds to develop the batter’s structure.
Prepare the pans. For a Bundt cake, spray the pan well with a nonstick spray. For Crunchy Feet, place the brioche pans on sheet pans (16 per half-sheet pan is a snug fit) and spray them liberally with a nonstick spray. For 9-inch-round cakes, line the bottom of each pan with parchment but do not spray the sides.
For a Bundt cake, fill the pan about three-quarters full by depositing the batter with the rubber spatula in small clumps around the prepared pan instead of by pouring it into one spot. Level the batter with the rubber spatula. Bake any leftover batter as Crunchy Feet or cupcakes. For Crunchy Feet, use a 2-ounce, trigger-release, ice cream scoop to deposit the batter into the prepared pans so they are three-quarters full. For 9-inch-round cakes, deposit the batter into three separate areas of the pan and smooth out with an offset spatula, making sure the pans are two-thirds full.
Follow these approximate bake times:
12-cup Bundt cake: 40-55 minutes at sea level; 65-70 minutes at high altitude.
Crunchy Feet: 15 minutes at sea level; 30 minutes at high altitude.
9-inch rounds: 30 minutes at sea level; 55 minutes at high altitude.
Once the top of the cake doesn’t jiggle in the center and the color is an even, deep orange, test for doneness by inserting a bamboo skewer into the middle of the cake. When the skewer shows just a touch of crumbs or comes out clean, the cake is done. Remove the pan from the oven and place on a heat-resistant surface or wire rack.
For the Bundt cake, once the cake has cooled for 5 to 10 minutes, remove it by inverting the pan onto a flat surface. Allow it to cool to room temperature, about 30 minutes, before glazing.
For Crunchy Feet, carefully invert the brioche pans to release the cakes 3 to 4 minutes after removing them from the oven — well before they cool completely. You may have to tap each pan firmly — or even slam it — against the sheet pan to release the cake. Place on a heat-resistant surface or wire rack to cool. Immediately soak the pans to make cleaning easier.
For the layer cake, cool to room temperature, 25 to 30 minutes, before removing from the pan. Use a small offset spatula to loosen the cake from the rim of the pan. Carefully invert each pan onto a flat surface to remove the layers. Remove the parchment from the bottom of each cake and wrap the cake tightly in plastic. Assembling a layer cake is easier if the cake is cold, so refrigerate the layers overnight or for up to five days before frosting.
Serving and storing:
Serve at room temperature either naked or with a dusting of confectioners’ sugar.
Store under a cake dome at room temperature, or wrapped in plastic in the fridge for up to 1 week. If frosted, store under a cake dome for up to 3 days, or in the fridge for up to 1 week. To store unfrosted cake longer, label, date, and store the plastic-wrapped cake in the freezer for up to 1 month.