Preheat oven to 350°F (175°C). Line an 8x8-inch baking pan with parchment paper, leaving overhang for easy removal.

In a bowl, cream softened butter and granulated sugar until light and fluffy. Mix in flour and salt until a crumbly dough forms.

Press the dough evenly into the prepared pan and bake for 18–20 minutes, until lightly golden around the edges.

While the crust bakes, whisk sugar and eggs until smooth. Add lemon juice, lemon zest, and flour, whisking until fully combined.

Fold chopped cranberries into the lemon mixture.

Pour filling over the warm crust and spread evenly.

Bake for 28–32 minutes, until the center is just set and no longer jiggly.

Cool completely, then refrigerate at least 2 hours before slicing into bars.