Step 1

Preheat the oven to 375F.

Step 2

Spray an 8-inch or 9-inch square pan with cooking spray and line with parchment paper.

Step 3

Combine graham cracker crumbs, butter, and sugar in a small bowl and stir until combined.

Step 4

Press the graham cracker crumb mixture into the bottom of the prepared pan and press down firmly. Use the bottom of a measuring cup to really pack it in.

Step 5

Bake the graham cracker crust for 7 minutes. Remove from the oven and let cool.

Step 6

Preheat the oven to 350F.

Step 7

Whisk the sweetened condensed milk, egg yolks, lemon juice and zest together in a medium bowl.

Step 8

Pour over cooled crust and bake for 25 minutes. Let the bars chill for at least 2 hours before serving.

Step 9

Combine lemon zest and sugar in a small bowl toss together gently making sure the zest is completely coated with the sugar. Let sit for 30 minutes.

Step 10

Sprinkle the candied lemon zest over the top of the cooled bars along with the powdered sugar if desired.

Step 11

Cut into bars. Store in an airtight container in the refrigerator.