Preheat oven to 325. Grease a 10 inch cake pan.
Melt butter in a small saucepan. Stir in brown sugar. Cook until sugar is dissolved, about 3 minutes. Stir in salt. Pour into bottom of cake pan.
Make circles of overlapping apple slices on top of the caramel.
Using a mixer, blend butter and sugar until fluffy. Gradually add egg, molasses, honey, and buttermilk.
Stop mixing and add dry ingredients/spices. Mix until just combined.
Pour batter over apples. Bake 50-55 minutes until set.
Allow to cool 10-15 minutes before inverting onto serving plate (one with rims is ideal or place something under your serving plate to catch any caramel that runs).
Serve warm (best the same day) with whipped cream.