Preheat your oven to 350°F (175°C) and grease a 9-inch springform pan.
In a small bowl, sift together the flour, baking soda, salt, cinnamon, and nutmeg.
In a large bowl, beat the butter and sugar until smooth. Add eggs one at a time, then stir in the vanilla.
Gradually mix the dry ingredients into the wet mixture until just combined, then fold in the diced apples and nuts (if using).
Transfer the batter into the prepared pan and bake for 35-40 minutes, or until a toothpick inserted in the center comes out clean.
Make the Caramel: While the cake is baking, combine the brown sugar, half & half, and butter in a small saucepan over medium-low heat. Stir frequently until smooth and combined (no need to bring to a boil).
Remove the cake from the oven and pour the caramel sauce over the top. Return the cake to the oven for another 10-15 minutes, or until the caramel is slightly cracked and the cake is fully cooked through.
Let the cake cool for at least 15 minutes before slicing and serving. Enjoy!
