Start by preheating your oven to 350°F and lightly greasing the baking pan. Mix graham cracker crumbs, melted butter, sugar, and lemon zest until moist. Press the mixture firmly into the pan, about an inch up the sides, and bake for 10 minutes. Let it cool to room temperature.
Whisk the egg yolks and condensed milk until smooth. Add lemon juice and zest, stirring until slightly thickened. Gently fold in the raspberries, being careful not to crush them to keep the filling beautifully pink and textured.
Pour the filling over the cooled crust and spread evenly. Bake for 15 minutes or until just set. Allow the bars to cool completely at room temperature, then refrigerate for at least an hour before cutting into squares