Step 1: Preheat your oven to 350°F (175°C) and line an 8×8 inch baking pan with parchment paper, leaving an overhang for easy removal.
Step 2: In a medium bowl, combine graham cracker crumbs, melted butter, and granulated sugar. Mix until the texture resembles wet sand.
Step 3: Press the crumb mixture firmly into the bottom of the prepared pan. Bake for 8-10 minutes until lightly golden. Set aside to cool slightly.
Step 4: In a large bowl, whisk together the egg yolks and sweetened condensed milk until smooth.
Step 5: Slowly whisk in the fresh lemon juice and zest. The mixture will begin to thicken naturally.
Step 6: Pour the lemon filling over the baked crust and smooth the top with a spatula.
Step 7: Bake for 15-18 minutes, or until the edges are set and the center has a slight jiggle. Do not overbake.
Step 8: Remove from the oven and allow to cool to room temperature, then refrigerate for at least 4 hours (or overnight) before slicing into Lemon Cream Pie Bars.