In a large bowl, cream 1 cup butter with an electric mixer until light and fluffy. Add 1 cup sugar and 1/2 cup brown sugar and beat until well combined. Beat in 2 eggs, one at a time, then stir in 1 teaspoon vanilla.
In a separate bowl, whisk together 2 1/2 cups flour, 1/2 teaspoon salt, and 1 teaspoon baking soda.
Gradually add the flour mixture to the butter mixture and mix until just combined.
Fold in 1 1/2 cups chopped Heath bars and 1/2 cup chopped walnuts by hand until evenly distributed.
Cover the dough and chill in the refrigerator for at least 1 hour.
When ready to bake, preheat the oven to 350°F and line baking sheets with parchment paper.
Scoop rounded tablespoons of dough (or use a 1-tablespoon cookie scoop) and roll into balls. Place the dough balls on the prepared baking sheets 2–3 inches apart.
Bake 10–12 minutes, or until the edges start to brown.
Allow the cookies to cool on the baking sheet until set (about 5 minutes), then transfer to a wire rack to cool completely.