In a bowl with an electric mixer mix together the flour, espresso powder, cinnamon, baking soda and powder, sugar, salt and orange zest. In a small bowl beat together the eggs and vanilla. Add them all at once to the dry ingredients and beat until a dough is formed. Stir in almonds.
Turn the dough out onto a floured board and form it into a ball. Halve it and form each half into a log approximately 12 inches long and 2 inches wide. Arrange logs on a buttered and floured baking sheet about 3 inches apart.
Bake logs in the middle of oven for 40 minutes or until they are firm all over and browned. Remove them from the oven, let cool for a few minutes. On a cutting board slice logs on a diagonal about 1/2 inch thick. Arrange the slices back on baking sheet and bake them for approximately 10 minutes on each side or until golden throughout.
Cool biscotti to room temperature. Store them in an airtight container in single layers between waxed paper for up to 2 weeks.