Preheat the oven to 350 degrees F. Line a baking sheet with parchment paper.
Place the flour, baking powder, salt, and cinnamon in a large bowl and stir with a spoon to mix well. Add the blueberries and stir to mix.
In another large bowl, whisk together the eggs, sugar, and vanilla extract until smooth. Gradually add the dry ingredients to the wet ingredients and stir to mix well.
Lightly dust a work surface with flour. Place the dough on the work surface and sprinkle lightly with more of the flour to prevent your hands from sticking to the dough. Knead the dough 4 or 5 times and, using your hands, shape into a log about 12 inches long and 4 inches wide. Place the dough on the prepared baking sheet.
Bake for 40 minutes, until firm to the touch.
Remove the baked loaf from the oven and keep the oven on. Cool the loaf on a wire rack. With a large metal spatula, transfer the loaf to a wire rack to cool.
Line a baking sheet with parchment paper. When the loaf is cool, using a serrated knife or electric knife, slice into 1/4-inch slices. Place the slices on the prepared baking sheet.
Bake for 10 to 15 minutes. Turn the biscotti and bake for another 10 to 15 minutes, until crispy.
Keep extra biscotti in an airtight container for up to 30 days or freeze for up to 2 months.