Preheat the oven to 325F and line 9 muffin cups with parchment or silicone liners. In a large bowl, whisk together the pecan flour, sweetener, cocoa powder, whey protein, baking powder, espresso powder, and salt. Stir in the eggs, hemp milk, butter, and vanilla extract until well combined. Divide the batter among the prepared muffin cups. Bake 20 to 30 minutes, until the tops are firm to the touch. Remove and let cool completely. In a large bowl, beat the butter with the cream cheese until smooth. Slow drizzle in the caramel sauce, beating on low. Add 1/2 cup of the powdered sweetener, beating until smooth. Add additional sweetener to taste. Beat in the caramel or vanilla extract. Pipe or spread the frosting onto the prepared cupcakes. Sprinkle with the chopped pecans, and drizzle with additional caramel sauce.