Preheat the oven to 325F and grease a 9x5 inch loaf pan. Line the bottom of the pan with parchment paper, leaving overhanging sides for easy removal. Grease the parchment.
In a medium bowl, whisk together the almond flour, cocoa powder, coconut flour, whey protein, baking powder and salt.
In a large bowl, beat the butter with the sweetener until well combined and fluffy, about 2 minutes. Beat in the eggs one at a time, scraping down the beaters and the sides of the bowl in between additions. Beat in the peppermint and vanilla extracts.
Add half of the almond flour mixture and beat until well combined, then beat in the cream and water. Beat in the remaining almond flour mixture until combined.
Transfer the batter to the prepared loaf pan and bake 60 to 70 minutes, until the top is firm to the touch and a tester inserted in the center comes out clean. Let cool completely in the pan and then use the overhanging parchment to lift out of the pan.
Chocolate Peppermint Ganache
In a small saucepan over medium heat, combine the heavy cream and the powdered sweetener. Whisk until smooth, then bring to a simmer. Remove from heat.
Add the chocolate chips and let sit a few minutes to melt. Add the peppermint extract and whisk until smooth.
Let the ganach sit 3 to 5 minutes to thicken. It should still be pourable but not runny. Drizzle over the top of the cake and let run down the sides. You can spread it over the sides if you prefer.
Refrigerate until set, about 30 minutes.
White Chocolate Drizzle
In a heatproof bowl set over a pan of barely simmering water, combine the white chocolate chips and the cocoa butter. Watch carefully and whisk until smooth (white chocolate can seize easily, especially this small amount).