01 - Preheat oven to 350°F. Line an 8-inch square baking pan with parchment paper, leaving overhang on two sides for easy removal.
02 - In a large bowl, whisk melted butter and sugar together until well combined. Add eggs and vanilla extract, beating until the mixture is smooth and slightly thickened. Fold in cocoa powder, flour, salt, and baking powder until just incorporated — do not overmix.
03 - Spread the batter evenly into the prepared pan. Bake for 22–26 minutes, or until a toothpick inserted in the center comes out with moist crumbs attached. Allow to cool completely in the pan on a wire rack.
04 - While the brownies cool, spread shredded coconut in an even layer on a baking sheet. Toast in the oven at 350°F for 5–7 minutes, stirring halfway through, until golden brown. Remove and set aside to cool.
05 - Place unwrapped caramel candies and milk (or cream) in a microwave-safe bowl. Heat in 30-second intervals, stirring between each, until the caramels are fully melted and the mixture is smooth and pourable.
06 - Fold the toasted coconut into the melted caramel until evenly coated. Spread the mixture in an even layer over the completely cooled brownies, pressing gently to adhere.
07 - Combine chopped chocolate and coconut oil (if using) in a microwave-safe bowl. Melt in 20-second intervals, stirring between each, until glossy and smooth.
08 - Drizzle the melted chocolate over the coconut-caramel layer in even lines or a zigzag pattern. Let the brownies set at room temperature, or refrigerate for 30 minutes until firm.
09 - Lift the brownies from the pan using the parchment overhang. Cut into 16 even squares with a sharp knife, wiping the blade clean between cuts for neat edges. Serve at room temperature.