Preheat the oven to 325F and line a baking sheet with a silicone mat or parchment paper.
In a large bowl, whisk together the almond flour, sweetener, cocoa powder, baking powder, and salt. Stir in the egg, melted butter, and vanilla extract until the dough comes together.
Turn the dough out onto the prepared baking sheet and form into a low, flat log, about 10 x 4 inches. Bake 25 to 30 minutes, until firm to the touch.
Remove from the oven and let cool 20 minutes. Reduce the oven temperature to 200F.
With a large sharp knife, gently slice the log into 15 even slices (try to cut straight down rather than sawing back and forth).
Separate the slices and spread them around the baking sheet with the cut sides exposed. Bake another 30 minutes, then turn off the oven and let stay inside until cool.
Toppings
In a heatproof bowl set over a pan of barely simmering water, melt the chocolate until smooth. Use a knife or offset spatula to spread chocolate on one side of each biscotto.
Sprinkle the pecans over the biscotti while the chocolate is still wet. Let set 30 minutes, or refrigerate to set the chocolate faster. Drizzle the biscotti with caramel sauce.
Let set 30 minutes, or refrigerate to set the chocolate and caramel faster.