Preheat the oven to 350 degrees F (176 C) and line a baking sheet with parchment paper.
In a medium mixing bowl, whisk together the sugar and melted coconut oil until thoroughly combined. Add the applesauce and almond extract. Whisk until well incorporated.
Add the brown rice flour, tapioca starch, almond flour, baking powder, and salt. Stir until no flour pockets remain. Add in the chopped chocolate and give it a good stir. The dough should be thick and moist.
Let the dough rest in the refrigerator for 5 minutes. It’s okay if it seems a little oily — this makes it less fragile when cutting.
When ready to bake, divide the dough into two equal amounts. Place each amount onto the parchment-lined baking sheet and shape into long skinny logs (~3 inches wide and 1 inch tall). Try to make them as uniform in size and shape as possible so they bake evenly.
Bake for 28-30 minutes – the edges should be golden and the center should be set with some give when touched. Remove the biscotti from the oven and set a timer for 5 minutes.
When the timer goes off and the biscotti is still very warm (don't wait or your biscotti may be crumbly!), slice biscotti into 1-inch thick slices. To do this, use a very sharp knife to saw the outer crust of the biscotti until you reach the center. Next, gently and slowly press down to fully cut. Be very patient at this point and if the crust of the biscotti begins to separate, you can gently press it back into the softer center. Place the biscotti back onto the baking sheet and bake again for 8-10 minutes on each side, until golden brown (16-20 minutes total).
While the biscotti is baking, you can toast the optional sliced almonds (for topping). Heat a small skillet over medium heat. Add the sliced almonds to the pan and toast until they are golden and fragrant. Move the almonds around the pan frequently to prevent burning. They toast quickly.
Remove the biscotti from the oven and let cool.
Meanwhile, if drizzling the biscotti with chocolate (optional), add the chocolate chips to a small glass or metal bowl. Carefully place the bowl on top of a saucepan with simmering water. Heat, stirring occasionally with a spatula or spoon, until melted and no lumps remain (~5 minutes). You can also melt the chocolate in a heat-proof bowl in the microwave in 30-second increments until melted. Remove chocolate from heat.
Once the biscotti have cooled, drizzle the melted chocolate across the top of them and sprinkle with toasted almonds. Place on a parchment-lined baking sheet or plate so the chocolate can set. To speed setting, pop in the freezer. Otherwise, let sit at room temperature until completely cooled.
Store covered at room temperature for 3-4 days (we found a large jar is ideal for storage). Will keep in the freezer for up to 1 month if well sealed.