Prepare a parchment-lined baking sheet and heat the oven to 350°F. The parchment provides a nonstick surface for shaping and baking the dough.

Beat the cooled, melted coconut oil with the monk fruit sweetener in a large bowl using an electric mixer, then incorporate the vanilla, almond extract, and egg. The mixture should look evenly blended before the dry ingredients go in.

Work the almond flour, baking powder, and salt into the wet mixture. Stop once you have a thick dough that holds together rather than a pourable batter.

Distribute the chopped sliced almonds through the dough with a spatula. Look for an even scattering of nuts without pockets of unmixed dough.

Transfer the dough to the parchment and press it by hand into a wide, flat log measuring about 9–12 inches long and 5–6 inches wide. An even surface and consistent thickness help the log bake uniformly.

Give the shaped log its first bake at 350°F for 18–20 minutes. Look for lightly golden edges rather than a deeply browned center.

Allow the baked log to rest at room temperature for at least 30 minutes, then freeze the whole log for 1 hour. The chilled crumb should feel firm enough to move and cut without collapsing.

Set the oven to 250°F before beginning the second bake. This gentler heat dries the slices without pushing the almond flour toward heavy browning.

Move the cold log to a cutting board and press an extra-sharp knife crosswise through it to make slices 1/2–3/4 inch wide, cutting diagonally if desired. Clean, intact edges indicate that the log is firm and the blade is cutting without dragging.

Arrange the slices gently on their sides on the baking sheet and bake for 30 minutes at 250°F, keeping the temperature no higher. The exposed cut faces should dry, although the warm cookies may still feel slightly yielding.

Leave the biscotti on the baking sheet until completely cool. The slices become firmer and develop their crisp snap as they lose heat.

Melt the chocolate in a microwave-safe bowl using 15-second bursts, stirring between each burst, then whisk in the espresso powder if using. The coating should look smooth enough to cover a cookie without clumps.

Dip one end or the top of each cooled biscotti into the melted chocolate, sprinkle with extra chopped sliced almonds, and transfer to a wire rack to set, using the refrigerator or freezer to firm the coating faster if desired. The finished chocolate should hold its shape rather than smear when handled.