2 cups all-purpose flour
1 teaspoon baking soda
¾ teaspoon kosher salt
1 cup (packed) dark brown sugar
⅓ cup granulated sugar
2 large eggs, room temperature
2 teaspoons vanilla extract
2 chocolate toffee bars, chopped into ¼-inch pieces (preferably Skor)
1½ cups chocolate wafers (discs, pistoles, fèves; preferably 72% cacao)
Flaky sea salt
Cook butter in a medium saucepan over medium heat, stirring often, until butter foams, then browns, 5–8 minutes. Transfer brown butter to a large bowl; let cool slightly. Whisk flour, baking soda, and kosher salt in a medium bowl. Add brown sugar and granulated sugar to cooled butter. Using an electric mixer on medium speed, beat butter mixture, scraping down sides of bowl, until incorporated, about 1 minute. Add eggs and vanilla and continue to beat until mixture lightens and begins to thicken, about 30 seconds. Reduce mixer speed to low; add dry ingredients and beat, scraping down sides and bottom of bowl, until just combined. Add candy and chocolate wafers and mix to combine with a spoon or spatula. Let sit at room temperature at least 30 minutes to hydrate flour; dough will look very loose but will thicken as it sits. Arrange a rack in center of oven; preheat to 375°. Line a rimmed baking sheet with parchment paper. Using a 1½-oz. ice cream scoop, portion dough and transfer to prepared sheet, spacing about 3½" apart (alternatively, form dough into ping pong ball-sized pieces with your hands). Do not flatten; cookies will spread as they bake. Sprinkle with sea salt. Bake cookies until edges are golden brown and firm but centers are soft, 9–11 minutes. Let cool on sheets 10 minutes, then transfer to a wire rack and let cool completely.