• Preheat oven to 350˚F (180˚C). Line a 9x13 inch (23x33 cm) baking dish with parchment or lightly grease.

To make the chocolate brownie layer:

• In the bowl of a stand mixer fitted with a paddle attachment or a large bowl, beat together the butter and sugar until light and fluffy. Beat in the eggs, one at a time, followed by the vanilla extract.
• In a medium bowl, whisk together the flour, cocoa powder, and salt. Beat into the butter mixture until just combined with no streaks remaining.
• Carefully spread the chocolate batter in the prepared baking pan in an even layer.

To make the coconut layer:

• Clean the bowl and beat together the coconut, condensed milk, egg white, and vanilla extract until combined.
• Scatter evenly across the chocolate layer in the pan. Gently smooth with a spoon or offset spatula.
• Bake in the preheated oven until set and the edges are golden, 25-30 minutes. Allow to cool completely to room temperature.

To make the chocolate frosting:

• In the bowl of a stand mixer fitted with a whisk attachment or a large bowl, beat together the powdered sugar, cocoa powder, butter, and vanilla extract. Slowly add the milk to create a light and smooth, spreadable frosting.
• Spread the frosting evenly over the cooled chocolate and coconut layers before cutting into small squares for serving.