Preheat oven to 350 F. Brush the bottoms and side of an 8 x 3 inch springform pan with melted butter.
Heat a medium sauce pan over medium heat. Add butter, sugar, brandy and salt. Cook for 1-2 minutes until slightly caramelized.
Stir in the vanilla, cinnamon and then the apples. Let simmer for 5-6 minutes or until applies have softened. Remove from heat and set aside.
To make cake, in a medium bowl, mix together flour, baking powder, salt and cinnamon and set aside.
In a small bowl, mix together dates, brandy and baking soda and set aside.
In a bowl of a stand up mixer or using a hand mixer, beat the butter and honey until creamy, 2-3 minutes. Beat in eggs one at a time until incorporated.
Mix in yogurt, dates and walnuts with a spatula.
Add in flour and mix with spatula until incorporated. Avoid over mixing the batter.
Pour batter in spring form pan and top evenly with caramelized apples. Pour any remaining sauce over apples.
Bake in a preheated oven for 50-60 minutes or until cake is set and apples have slightly caramelized on top. You can poke a toothpick in the centre of the cake to ensure it comes out clean as your cake is then done.
Let the cake rest for 5 minutes and then gentle remove the side of the pan. Once cake as cooled enough to handle, gently transfer it from the bottom of the pan to a serving plate.
Garnish with ground walnuts before serving.