Salted Crinkle Top Brownie Cookie Bars

Name: Salted Crinkle Top Brownie Cookie Bars
Prep time: 15 min
Cook time: 45 min
Total time: 1 h
Cuisine: American
Ingredients: 1 stick (1/2 cup) salted butter, at room temperature; 1/3 cup dark brown sugar; 2 tablespoons granulated sugar; 1 large egg, at room temperature; 1 teaspoon vanilla extract; 1 cup + 2 tablespoons all-purpose flour; 1/2 teaspoon baking soda; 1/2 teaspoon kosher salt; 3/4 cup semi-sweet chocolate chips; 1 cup Nutella; 2 large eggs; 4 tablespoons salted butter, melted; 2 teaspoons pure vanilla extract; 1/2 cup all-purpose flour; 1/2 cup semi-sweet chocolate chunks ((optional)); flaky sea salt