01 -
Preheat oven to 350°F.
02 -
Microwave chocolate and butter in 30-second intervals until smooth.
03 -
Whisk sugars, eggs, and vanilla. Stir in chocolate mixture.
04 -
Mix in flour and salt. Fold in walnuts if using.
05 -
Pour into crust, bake 25-30 minutes until edges set but center soft.
06 -
Let cool on wire rack before slicing.