Crunch Bars

Ingredients

• 1 cup (2 sticks) unsalted butter, room temperature, plus more for dish
• 1/2 cup (packed) light brown sugar
• 1/4 cup sugar
• 1/2 teaspoons fine sea salt
• 1 1/2 teaspoons vanilla extract
• 1 1/2 cups all-purpose flour
• 6 ounces semisweet or bittersweet chocolate or high-quality milk chocolate, finely chopped
• 1-1 1/2 cups assorted toppings, such as cocoa nibs, crushed candy, toasted chopped almonds and pistachios, lightly toasted coconut, and popcorn
• Flaky sea salt (such as Maldon)