Prep the pan and oven. Heat the oven to 350°F (175°C). Generously grease a 10–12 cup Bundt pan with butter or baking spray and dust with flour, tapping out the excess. This helps prevent sticking, especially in detailed pans.

Whisk dry ingredients. In a large bowl, whisk flour, granulated sugar, brown sugar, baking powder, baking soda, salt, cinnamon, and nutmeg. Break up any brown sugar clumps as you go.

Mix the wet ingredients. In a separate bowl, whisk oil, applesauce, eggs, vanilla, and buttermilk until smooth. The applesauce adds moisture without making the batter heavy.

Combine wet and dry. Pour the wet mixture into the dry ingredients. Stir gently with a spatula just until no flour streaks remain. Do not overmix—this keeps the crumb tender.

Fold in apples (and nuts, if using). Stir in the diced apples and nuts until evenly distributed. The batter will be thick and chunky—that’s what you want.

Fill the Bundt pan. Spoon the batter into the prepared pan. Smooth the top and tap the pan firmly on the counter a couple of times to release air bubbles.

Bake. Bake for 45–55 minutes, or until a toothpick inserted near the center comes out with a few moist crumbs. If the top browns too fast, tent with foil for the last 10 minutes.

Cool in the pan. Let the cake cool in the pan on a rack for 15–20 minutes. Then carefully invert onto a cooling rack and lift off the pan. Cool completely before drizzling.

Make the caramel drizzle. Add sugar to a heavy saucepan over medium heat. Cook, stirring with a heatproof spatula, until the sugar melts into a deep amber liquid. Add butter carefully (it will bubble), stirring until smooth. Slowly pour in warm cream, whisking constantly. Simmer 30–60 seconds until glossy. Remove from heat and stir in vanilla and salt. Let cool 10–15 minutes to thicken slightly.

Drizzle and serve. Place the cooled cake on a serving plate. Spoon the warm caramel over the top, letting it run down the sides and into the ridges. Slice and enjoy.