Preheat your oven to 350°F (175°C). Grease and flour three 8-inch round cake pans.

In a large mixing bowl, sift together the dry ingredients including flour, baking powder, baking soda, salt, ground cinnamon, ginger, pumpkin pie spice, and nutmeg.

In another bowl, whisk together the wet ingredients: canola oil, brown sugar, granulated sugar, vanilla extract, sour cream, eggs, and buttermilk. Mix until well combined and smooth.

Gently fold the wet ingredients into the dry mixture until just combined, being careful not to overmix.

Divide the batter evenly among the prepared cake pans. Bake for 20-24 minutes, or until a toothpick inserted comes out clean.

While the cakes are cooling, prepare the salted caramel. In a medium saucepan, melt sugar over medium heat, stirring constantly until it turns a deep amber color.

In a skillet over medium heat, melt butter and add sliced Gala apples. Sprinkle with brown sugar and cornstarch, cooking for about 5-7 minutes until softened.

For the frosting, beat softened unsalted butter until creamy, then gradually add sifted powdered sugar and beat until fluffy.

Trim the tops of the cooled cake layers if necessary. Place one layer on a plate, spread frosting, add apple filling drizzled with caramel, and repeat with the second layer.

Cover the assembled cake with frosting and drizzle additional salted caramel on top. Let it set in the refrigerator for about 30 minutes.

Slice your cake and serve it to friends and family. This cake is fantastic on its own or paired with vanilla ice cream.