iRum Cake

1. Preheat the oven to 325°F (165°C). Grease a 12-cup bundt pan with the unsalted butter (for pan), dust with the all-purpose flour (for pan), then scatter the chopped walnuts evenly in the bottom.

2. In a bowl, whisk the cake flour, baking powder, and kosher salt until evenly combined.

3. In a large mixing bowl, beat the unsalted butter (for batter) and the granulated sugar (for batter) with a mixer on medium speed until pale and fluffy, 3–4 minutes.

4. Beat in the large eggs one at a time, letting each incorporate before adding the next, then mix in the vanilla extract.

5. In a measuring cup, whisk the whole milk and the dark rum (for batter) to blend.

6. With the mixer on low, add the dry ingredients in 3 additions alternating with the milk–rum mixture in 2 additions, beginning and ending with dry. Mix just until combined; scrape the bowl once.

7. Scrape the batter into the prepared pan over the walnuts and smooth the top; tap the pan once or twice to release air bubbles.

8. Bake until deep golden and a tester inserted near the center comes out with a few moist crumbs, 50–60 minutes.

9. During the last 10 minutes of baking, make the syrup: combine the unsalted butter (for syrup), the granulated sugar (for syrup), and the water in a small saucepan. Bring to a simmer over medium heat, stirring to dissolve the sugar, then simmer gently 3–4 minutes until slightly thickened. Remove from heat and stir in the dark rum (for syrup).

10. Set the hot cake on a rack. Immediately poke holes all over the surface with a skewer and slowly spoon about half of the hot syrup over the cake while it is still in the pan, letting it soak in. Cool 20 minutes.

11. Invert the cake onto a serving platter. Poke a few holes on top if desired and brush or spoon the remaining syrup over the warm cake until absorbed.

12. Let the cake cool completely until set and barely tacky to the touch, about 45–60 minutes, then slice and serve.