Preheat the oven to 350°F. Line a large baking sheet with a Silpat or parchment paper; set aside.
In a large bowl, whisk together 3 cups all-purpose flour, 1 teaspoon sea salt, 1 teaspoon baking soda, and 1 1/2 teaspoons baking powder; set aside.
In the bowl of a stand mixer (or using a hand mixer and large bowl), cream 1 cup unsalted butter (room temperature) with 1/2 cup granulated sugar and 1 1/2 cups packed light brown sugar until light and creamy, about 5 minutes.
Add 2 large eggs and 2 teaspoons vanilla extract to the creamed butter and sugars; beat until combined, about 2 minutes.
With the mixer on low speed, slowly add the dry ingredients to the wet ingredients and mix just until the flour is incorporated. Do not overmix.
Using a spatula, stir in 1 cup semi-sweet chocolate chips, 3/4 cup chopped hazelnuts (skins removed), and 3/4 cup Heath Toffee Bits until evenly distributed.
Drop about 2 tablespoons of dough per cookie onto the prepared baking sheet, spacing the cookies about 2 inches apart. (Use a cookie scoop or two spoons if desired.)
Lightly sprinkle each cookie with the extra sea salt.
Bake for 10–12 minutes, or until the edges are slightly golden and the centers appear set.
Remove the baking sheet from the oven and let the cookies cool on the sheet for 2–3 minutes, then transfer the cookies to a wire cooling rack to cool completely.