Preheat the oven to 350ºF. Line your baking sheet with parchment paper.
In a large bowl, combine the sugar and eggs. Whisk until the mixture is light yellow and slightly thickened, about 4 minutes. Mix in the almond and vanilla extracts.
Fold in flour, almond flour, baking powder, and salt. When the dough is nearly all combined, fold in the almonds.
Form the dough into a 9 inch by 6 inch rectangle on your lined baking sheet. It should be roughly 1 inch tall. Bake for 30 minutes, until lightly golden brown.
Cool the biscotti on the pan for 15 minutes. While cooling, reduce the oven temperature to 300ºF.
Slice your biscotti into 16 planks. Lay them cut side down on the baking sheet. Bake for 15 minutes. Flip the biscotti over and bake on the other side for an additional 15 minutes or until dry.
Once biscotti are golden brown, remove from baking sheet to wire cooling rack to cool completely, about 20 minutes.
Chop the white chocolate and place it in a microwave-safe bowl with the coconut oil. Melt in 30-second intervals at regular power until starting to melt but chunks are still visible. Stir to finish melting. The residual heat from the bowl is enough to finish melting without overheating the white chocolate.
Dip the bottoms of your biscotti in the white chocolate. Place them on a piece of parchcment paper to set. Drizzle any remaining chocolate over the sides. Allow the chocolate to set before storing away in an airtight container.