Preheat the oven to 350F and line two large baking sheets with parchment paper.

Sift or whisk together the flour, baking powder, baking soda, and salt in a medium bowl. 

In a stand mixer (or using a handheld electric mixer and a large bowl), beat the butter and 1 cup sugar on medium speed, scraping down the sides of the bowl as necessary, until pale and creamy 2-3 minutes. Add the eggs, one at a time, and beat to combine, followed by the vanilla and lemon juice, beating after each addition. Add the flour mixture in 2 additions and beat on low until just combined, then fold in the almonds with a spatula. The dough should be soft and spreadable.

Divide the dough into 4 equal portions. Set 2 parts of the dough on one of the prepared baking sheets and use a butter knife or offset spatula to spread each part into a long, flat rectangle about 9x4 inches and about ½ inch thick, leaving about 2 inches in between. Repeat with the remaining 2 parts of dough and the second baking sheet.

Bake, rotating the pans front to back halfway through, until puffed and lightly browned, about 20 minutes. Remove from the oven and let cool slightly (leave the oven on). Meanwhile, in a small bowl, stir together the remaining 1 cup sugar and the cinnamon.

Slice the rectangles crosswise into pieces ¾ inch wide. Turn the pieces on their sides and sprinkle generously with half of the cinnamon sugar. Return to the oven and bake 10 more minutes. Remove the pan from the oven again, flip the cookies to the other side, and sprinkle with the remaining cinnamon sugar. Return to the oven and bake until firm and crisp, another 10 minutes. Set the baking sheets on wire racks to cool for 5 minutes, then transfer the cookies to the racks to cool completely.