Preheat oven to 325 degrees Fahrenheit, Line baking sheet with parchment paper.
Mix together almond flour, swerve, baking powder, sea salt, lemon zest and pistachios in a large bowl.
In another bowl mix together melted butter, egg, and vanilla.
Add wet ingredients to dry ingredients.
Mix well.
Place dough onto baking sheet and form into a log.
The dough is rather soft making it difficult to slice after the first bake. *Tip, this is optional: using a sharp knife, precut the slices but leave it in its log shape, before the first initial bake. This makes it easier to slice after.
Bake 25 minutes.
Let cool for 30 minutes.
Reduce oven to 250 degrees Fahrenheit.
Completely slice the precut biscotti and lay flat on baking tray.
Bake for 15 minutes.
Flip the biscotti over.
Bake for an additional 15 minutes.
Turn off oven. Allow biscotti to dry completely in warm oven until lightly brown, about an hour.