Preheat the Oven: Preheat your oven to 350°F (175°C) and grease a 9-inch springform pan.
Mix Dry Ingredients: Sift together flour, baking soda, salt, cinnamon, and nutmeg. Set aside.
Cream Butter and Sugar: Beat butter and sugar until creamy. Add eggs one at a time, then mix in vanilla.
Combine and Fold: Gradually add dry ingredients to wet mixture until combined. Fold in diced apples and nuts.
Bake the Cake: Transfer batter to the springform pan and bake for 35-40 minutes.
Prepare Caramel: While the cake bakes, combine brown sugar, half & half, and butter in a saucepan over medium-low heat. Stir until smooth.
Add Caramel: Pour caramel over the cake after 30 minutes of baking. Return to the oven for an additional 10-15 minutes.
Cool and Serve: Let the cake cool for at least 15 minutes before slicing and serving.