01 - Preheat oven to 350°F (175°C). Line an 8x8-inch baking pan with parchment paper, ensuring an overhang for easy removal.
02 - In a medium mixing bowl, combine the all-purpose flour, powdered sugar, and salt. Incorporate the cold, cubed butter using a pastry blender or your fingertips until the mixture resembles coarse crumbs.
03 - Evenly press the crust mixture into the bottom of the prepared baking pan. Bake for 15 minutes, or until the crust achieves a lightly golden hue.
04 - While the crust is baking, whisk together the drained ricotta cheese, granulated sugar, large eggs, all-purpose flour, lemon zest, fresh lemon juice, and vanilla extract in a large bowl until the mixture is smooth and creamy.
05 - Pour the prepared filling evenly over the hot shortbread crust and smooth the surface. Return the pan to the oven and bake for an additional 25 minutes, or until the center is just set and exhibits a slight wobble when gently shaken.
06 - Remove the pan from the oven and allow the bars to cool completely in the pan. For best results, chill the bars in the refrigerator for at least 2 hours before slicing.
07 - Dust with powdered sugar before serving, if desired.