Preheat oven to 350°F. Grease and flour two 8-inch round pans.
In a medium size mixing bowl, combine all-purpose flour, baking powder, salt, cinnamon, nutmeg and clove. Whisk until combined and set aside.
Cream together butter and sugar in a mixing bowl on medium speed. Add eggs and vanilla, mix on medium speed for 1 minute, scraping down the sides of the bowl.
Working in 3 batches alternate adding dry ingredients and apple cider, starting and ending with the dry ingredients.
Mix on medium speed until incorporated, about 1 to 2 minutes.
Divide the batter between the two cake pans. Bake for 25 to 28 minutes or until a toothpick inserted into the center of the cake comes out mostly clean (a few crumbs is fine.) For 9-inch cake pans, bake for slightly less time as the layers will be thinner, about 22 to 25 minutes.
Caramel Apple Filling
In a sauté pan, heat the butter over medium high heat. Add the apple slices and sauté until coated in the butter and slightly soft, about 2 minutes. Sprinkle the cinnamon over the apples and add the caramel to the pan. Reduce the heat to low and bring the sauce to a boil.
Remove from heat and let cool completely in the refrigerator about 20 minutes until sauce is thickened.
Salted Caramel Buttercream
In the bowl of a standing mixer, cream the butter until pale and fluffy on medium high speed. Beat in the cream cheese, scraping down the sides of the bowl and beating until combined.
On the lowest speed add in the confectioners sugar 1 cup at a time. Bring speed up to medium high and beat for 1 full minute. Add the salted caramel sauce and beat for 2 minutes, stoping half way to scrape the sides and bottom of the bowl.
Assembling the cake
On the first layer of cake, pipe a wall around the outside edge. About two times around should be high enough to contain the filling. Fill the inside with the cooled caramel apple filling. Top with the second layer of cake and press down lightly.
Frost the outside of the cake with the remaining salted caramel frosting. Top with cinnamon sticks.
Optional: Place walnuts in a plastic food bag and crush with a meat mallet or rolling pin. Lightly stick to the bottom half of the frosted cake.
Since there is cream cheese in the frosting, store the finished cake in the refrigerator. Take out about an hour before serving.
Chopped walnuts or pecans can be used instead of whole walnuts.
Store-bought caramel can be substituted for homemade Small Batch Caramel Sauce. If opting to make the caramel sauce, be sure to allow for LOTS of time to cool. I highly recommend making it the day before so it will be room temperature. If using store-bought, Trader Joe's makes a salted caramel sauce that is almost identical to the linked recipe above!
This recipe can be converted into cupcakes and makes roughly 24 cupcakes. For the filling, dice the apples small and stuff them inside the center of the cupcakes.