Preheat your oven to 325-F and line 2 baking trays with parchment paper for easy cleanup.
Use a double boiler to melt the butter, 5 ounces of the semisweet chocolate, and the unsweetened chocolate together until combined. Set aside to cool slightly.
Transfer the melted chocolate and butter to a medium-sized bowl and mix in the sugar.
Add the eggs, mixing after each egg, then add the vanilla.
Add the flour and mix until combined, scraping down the sides of the bowl as needed.
Stir in the remaining chopped semisweet chocolate and chopped walnuts.
Scoop 2 tablespoon balls of dough and place them about 2 inches apart on the baking sheets. Flatten the dough balls lightly with a spatula.
Bake at 325-F for 9-11 minutes or until set.
Cool on a wire rack, then dig in!
Notes
Chef Jenn's Recipe Tips
To achieve the perfect texture, remember not to overmix the batter when adding flour. Mix until just combined.
Get creative with your add-ins! Instead of walnuts, try substituting them with pecans, almonds, or even a handful of chocolate chips for an extra dose of chocolatey goodness.
Bake your cookies in the middle of the oven so they don’t get too brown on the bottom.