Preheat oven to 350°F. Line a 9×13-inch pan with parchment and spray lightly.
Whisk 2 cups all-purpose flour, ¼ cup granulated sugar, and a pinch of salt. Stir in 1 cup melted butter until mixture forms coarse clumps. Press into the pan and bake for 15 minutes.
2 cups all-purpose flour, 0.25 cup granulated sugar, 1 pinch salt
Filling
In a bowl, whisk 4 large eggs with 2 cups granulated sugar until smooth. Stir in zest of 3 lemons and juice of 3 lemons (about ½ cup).
1 cup unsalted butter, melted, 2 cups granulated sugar, 4 large eggs
Add ¼ cup all-purpose flour, 1 teaspoon baking powder, and a pinch of salt. Fold in 1 cup cranberries.
3 lemons lemon zest, 0.5 cup lemon juice (about 3 lemons), 0.25 cup all-purpose flour, 1 teaspoon baking powder
Pour filling over hot crust and bake 22–25 minutes until just set in the center.
Let cool on a rack for 1 hour; chill 2 hours. Dust with powdered sugar and slice into bars.
Notes
Chill bars completely before slicing for neat edges.Line pan with overhanging parchment for easy removal.