Spread almonds on a baking sheet and toast them in oven until lightly golden. Let cool. Coarsely chop half the nuts.
In bowl of stand mixer, combine flour, sugar, salt and baking soda.
Beat in eggs, then stir in the whole and chopped nuts. Mix to obtain a firm dough. NOTE: Dough should be sticky. Do not add extra flour.
On a floured work surface, knead briefly, then divide dough into 2 pieces. Roll each piece under your hands into a cylinder 15 inches long and about 1-½ inches in diameter. Place 2 rolls, well separated, on baking sheet and bake 20 to 25 minutes, until very lightly browned and firm to the touch. The dough will spread during baking.
With a spatula, carefully transfer the rolls to a cutting board and slice each one diagonally about ½-inch thick. Remove the parchment paper and set the wire rack on the baking sheet, and then lay out the biscotti on the rack. Return to the oven for 20 to 25 minutes, or until very firm and crisp.
Cool on the rack, then transfer biscotti to an airtight container for long keeping.
Dip the biscotti in dark chocolate and allow the chocolate to set before serving.
Traditional biscotti are flavored with anise; however, I have an intense dislike for that particular flavor, so I never use it. If you like anise, include ½ to 1 teaspoon of anise extract when you add the eggs.