Make The Toffee Sauce - Place ¼ cup of butter and ¼ cup of sugar in a small-medium pot and cook over medium heat. Stir gently until the butter melts to help dissolve the sugar, but once the butter has melted do not stir again. Cook butter and sugar to a deep amber colour and remove from heat. Slowly and carefully add ¼ cup of 35% heavy cream cream, whisking constantly. Set aside to cool.
Preheat oven to 350ºF. Generously butter a 9-inch round cake pan. Line buttered pan with parchment paper and grease the parchment with more butter.
Peel, core, and slice SweeTango apples to your preference. Pour toffee sauce into prepared cake tin. Arrange apple pieces gently on top of toffee sauce in tin.
In a medium-large bowl mix spelt flour, ground cardamom, ground ginger, cinnamon, nutmeg, allspice, ground cloves, white pepper, baking powder, and salt to combine. Set aside.
In another bowl whisk sugar and melted butter until sugar dissolves. Add eggs, one at a time, and whisk until combined. Add milk and vanilla to egg mixture and continue to whisk until well combined.
Slowly fold flour mixture into egg mixture. When all dry ingredients have been added continue to fold until flour streaks just disappear. Gently scoop and spread cake batter evenly on top of apples in cake tin, trying not to disturb the arrangement of the apples in the toffee sauce. Place the pan in the oven and bake 30-35 minutes, or until an internal temperature reads 200-205º. Cool cake on a rack for 10 minutes then turn out onto a plate or platter. Serve warm or cold, plain or with whipped cream.