Mix each mixture separately, white after dark but follow the same procedure for both.
- In a double boiler, melt chocolate and butter together.
- Measure out all the rest of the ingredients.
- In mixer with whip, put eggs and vanilla in bowl and whip on low speed for 2 minutes.
- In large bowl, sift together flour, sugar and salt.
- Turn mixer down to very low and add flour mixture to eggs until just mixed. Do not over mix.
- Remove chocolate from stove and whip until batter is incorporated into chocolate and smooth.
- Turn mixer back on low and pour chocolate into batter.
- When chocolate is blended in, add nuts (for dark mix) or chocolate chips (for white mix).
- Dry sheet pan and spray with food release then put parchment paper on pan and spray it with food release as well.
- Pour dark batter onto pan and spread evenly.
- Pour white batter on top. Use a fork to dig some of the dark batter up to the top and slightly mix together batters without over mixing to create a zebra effect.
- Bake 350 45-50 minutes. Better a little under baked then over baked.