Prep and Preheat: Start by preheating your oven to 350°F (175°C). Grease your bundt or cake pan well and lightly dust it with flour to ensure the cake releases easily after baking. Gather all your ingredients so you’re ready to go.
Mix Dry Ingredients: In a medium bowl, whisk together the flour, baking powder, baking soda, cinnamon, nutmeg, and salt. Set this aside while you work on the wet ingredients. This helps evenly distribute the leavening agents and spices for a balanced flavor and rise.
Cream Butter and Sugar: Using an electric mixer or a sturdy whisk, beat the softened butter and sugar on medium speed until the mixture is light and fluffy, about 3 to 5 minutes. This step is key for a tender crumb, so don’t rush it.
Add Eggs and Vanilla: Beat in the eggs one at a time, making sure each is fully incorporated before adding the next. Stir in the vanilla extract. The batter might look slightly curdled here, but that’s okay.
Combine Wet and Dry: Alternately add the dry ingredient mixture and the apple cider to the butter mixture, starting and ending with the dry ingredients. Mix gently between additions. Finally, fold in the sour cream or Greek yogurt to add moisture and richness.
Bake and Cool: Pour the batter into your prepared pan and smooth the top with a spatula. Bake for about 40 minutes, or until a toothpick inserted in the center comes out clean. Let the cake cool in the pan for 15 minutes, then transfer it to a wire rack to cool completely before frosting.
Make the Buttercream: While the cake cools, beat the softened butter on medium speed until creamy. Gradually add the powdered sugar, mixing well. Slowly add the caramel sauce, vanilla, and sea salt, beating until smooth. Adjust the consistency with heavy cream or milk, adding a tablespoon at a time until it’s spreadable but still thick.
Frost the Cake: Once the cake is completely cool, generously frost the top and sides with the salted caramel buttercream. Sprinkle a little extra flaky sea salt on top for that perfect salty-sweet finish.