Step 1

Make the crust: Line a 9x13-inch baking pan with parchment paper so that there is extra paper hanging off the two long sides like a sling, as described in this tutorial. Coat the paper and exposed sides of the pan with cooking spray; set aside.

Step 2

Place the nuts in the bowl of a food processor fitted with the blade attachment and pulse until coarsely ground, about 15 (1-second) pulses. Add the flour, sugar, cinnamon, and salt, and pulse until finely ground, about 10 (1-second) pulses. Scatter the butter over the top of the flour-nut mix and pulse until the mixture forms moist clumps, 20 to 25 (1-second) pulses.

Step 3

Transfer the mixture into the baking dish and press into the dish with your hands or the bottom of a floured measuring cup, making it as even as possible. Refrigerate at least 30 minutes. Twenty minutes before the crust is ready, arrange a rack in the middle of the oven and heat to 350°F.

Step 4

Bake the crust until beginning to brown around the edges, 20 to 25 minutes. Meanwhile, prepare the cranberry curd.

Step 5

Make the cranberry curd: Place the cranberries and water in a medium saucepan over medium heat and bring to a boil over medium-high heat. Continue to cook, stirring occasionally, until all the cranberries have burst open and are mushy, about 5 minutes. Meanwhile, fit a fine-mesh strainer over a large bowl.

Step 6

Pour the cranberry mixture into the strainer and press the cranberry purée through using a spatula until only pulp remains in the strainer. Set the purée aside to cool to room temperature, about 10 minutes. Meanwhile, discard the contents of the strainer and clean the strainer and the saucepan for reuse.

Step 7

Add the sugar, eggs, egg yolks, lemon juice, and salt to the cranberry purée and whisk until smooth. Return the cranberry mixture to the saucepan over medium heat. Stir the curd continuously, making sure to scrape the bottom and corners of the pan, until it comes to a simmer and thickens slightly, coats the back of a spoon, and registers about 150°F on an instant-read thermometer (there's some wiggle-room, so don't fret about being exact), 5 to 11 minutes.

Step 8

Remove the pan from the heat, add the butter all at once, and stir until completely melted. Pour the curd through the strainer again into a clean bowl to strain out any small chunks of cooked egg. Pour the warm cranberry curd onto the crust and spread into an even layer.

Step 9

Bake until the curd is set but still jiggles slightly in the center, 10 to 15 minutes. Place the pan on a wire rack and cool for 1 hour. Refrigerate until chilled through, at least 2 hours and up to 1 day.

Step 10

When ready to serve, run a thin knife around the edge of the pan to loosen the cranberry bar slab. Use the parchment paper as handles to lift the slab from the pan onto a cutting board. Trim off the sides to make even edges if desired. Cut into 24 pieces. Dust the tops of the bars with powdered sugar, which will melt into the cranberry curd and make a sweet glaze. Garnish each square with the candied citrus zest if desired.