Preheat the oven to 350°F and set an oven rack in the middle position. Grease a 9-inch springform or regular cake pan with butter or nonstick cooking spray. If using a regular cake pan, line the bottom of the pan with parchment paper and grease again.

In a small bowl, whisk together the flour, baking powder and salt.

Using a handheld mixer with beaters or a stand mixer with the paddle attachment, cream the butter and granulated sugar until light and fluffy, about 3 minutes. Add the eggs, one at a time, beating well and scraping down the sides of the bowl after each addition. Beat in the vanilla and rum. Dont worry if the batter looks grainy at this point; thats okay.

Add the flour mixture and mix on low speed until just combined. Using a rubber spatula, fold in the chopped apples and walnuts.

Scrape the batter into the prepared pan and even the top. Sprinkle evenly with 1 tablespoon of turbinado sugar. Bake for about 40 minutes, or until the cake is golden and a toothpick inserted into the center comes out clean. Allow the cake to cool on a rack in the pan.

Once cool, run a blunt knife around the edges of the cake. If using a springform pan, remove the sides. If using a regular cake pan, carefully invert the cake onto the rack, remove the parchment paper, flip over on to a platter. If desired, using a fine sieve, dust with confectioners sugar. Cake can be served warm or room temperature, plain or with lightly sweetened whipped cream or custard or vanilla ice cream.

MJF Notes: To the original recipe I added cinnamon, allspice and walnuts. Maybe try brown sugar next time. I experimented using Instant Pots Air Fryer Lid. Divided batter between 2 6 cake pans. Baked one in oven at 345 convection for 30 mins (thinner cake levels). The other in the Instant Pot. 345 was too hot and top browned too fast. Lowered to 330, perfect. Some tips I read said baking temps should be lowered.

Creme Anglaise: Bring milk, cream to a boil in microwave. Meanwhile, fill a large bowl with ice cubes, and set aside a smaller bowl that can hold finished cream.

Whisk yolks and sugar together in a heavy-bottomed saucepan. Whisking constantly, drizzle in one-quarter of the hot liquid. When yolks are warm, add the rest of the liquid in a steadier stream. Remove pod, return pan to medium heat and, whisking vigorously, cook cream until it thickens slightly, lightens in color and reaches 180 degrees. Alternatively, you can coat a wooden spoon with cream, then draw your finger across it; if cream doesnt run into the track you have created, its done.

Immediately remove pan from heat, add vanilla and whiskey. Allow cream to rest for a few minutes until it reaches 182 degrees. Set bowl into ice bath, add cold water and, stirring frequently, cool completely. Cover cream and chill, if possible for 24 hours.