01 - Preheat oven to 350°F. Line an 8-inch square baking pan with parchment paper, leaving enough overhang on two sides to lift the brownies out later.
02 - In a large mixing bowl, whisk together the melted butter and granulated sugar until well combined. Add the eggs one at a time, beating after each addition, then stir in the vanilla extract until the mixture is smooth and glossy.
03 - Sift the cocoa powder, all-purpose flour, salt, and baking powder directly into the wet mixture. Fold gently with a spatula until just combined — do not overmix to keep the brownies fudgy.
04 - Pour the batter into the prepared pan and spread it into an even layer. Bake for 22 to 26 minutes, or until a toothpick inserted into the center comes out with moist crumbs attached. Allow the brownies to cool completely in the pan.
05 - While the brownies cool, spread the shredded coconut evenly on a rimmed baking sheet. Toast in the oven at 350°F for 5 to 7 minutes, stirring halfway through, until the coconut turns a deep golden color. Remove and set aside to cool.
06 - Place the unwrapped caramel candies and milk or heavy cream in a microwave-safe bowl. Heat in 30-second intervals, stirring thoroughly between each burst, until the caramel is completely melted and silky smooth.
07 - Fold the toasted coconut into the melted caramel until evenly coated. Spread the coconut-caramel mixture in a thick, even layer over the completely cooled brownie base, pressing gently to adhere.
08 - Place the chopped semi-sweet chocolate and coconut oil (if using) in a microwave-safe bowl. Melt in 20-second intervals, stirring between each, until the chocolate is smooth and free of lumps.
09 - Using a fork or spoon, drizzle the melted chocolate in zigzag lines across the coconut-caramel layer. Let the brownies set at room temperature, or refrigerate for 30 minutes until the chocolate firms up.
10 - Grip the parchment overhang and lift the entire slab of brownies out of the pan. Place on a cutting board and slice into 16 even squares using a sharp knife. Wipe the blade clean between cuts for neater portions.