Preheat the oven to 350°F (175°C). Line a baking sheet with parchment paper or lightly grease it.

In a large bowl, whisk together 2 cups flour, 3/4 cup sugar, 1 1/2 teaspoons baking powder, and 1/2 teaspoon cinnamon. Stir in the 6 ounces whole unblanched almonds.

In a separate bowl, whisk the 3 eggs with 2 teaspoons vanilla until combined.

Pour the egg mixture into the dry ingredients and use a rubber spatula to stir until a stiff dough forms.

Lightly flour a work surface. Turn the dough out onto the surface, divide it in half, and shape each half into a cylinder (log) a little shorter than your baking sheet and about 1 1/2 inches to 2 inches thick.

Place the two logs on the prepared baking sheet, leaving space between them and from the edges of the pan.

Bake for 25 to 30 minutes, until the logs have risen, are nearly doubled in size, and feel firm to the touch. Remove the pan and transfer the logs to a wire rack to cool completely.

When the logs are completely cool, place one log on a cutting board and, using a sharp serrated knife, cut it diagonally into slices about 1/3 inch thick. Repeat with the second log.

Arrange the slices cut side down on the prepared baking sheet in a single layer with space between pieces. Bake for 15 to 20 minutes, turning the biscotti once halfway through, until they are well toasted and golden.

Transfer the biscotti to a wire rack to cool completely.

Store the cooled biscotti between sheets of parchment in a covered, airtight container.