01 - 
                Preheat oven to 175°C and lightly grease a 33 x 46 cm sheet pan.
              
              
              
                02 - 
                Combine 227 g unsalted butter and 240 ml water in a medium saucepan; bring to a boil, then remove from heat.
              
              
              
                03 - 
                In a large bowl, whisk together 400 g granulated sugar, 250 g all-purpose flour, 0.5 teaspoon salt, and 1 teaspoon baking soda.
              
              
              
                04 - 
                Pour hot butter-water mixture over dry ingredients and stir until thoroughly combined.
              
              
              
                05 - 
                Add 2 large eggs, 120 g sour cream, and 1 teaspoon vanilla extract; mix until batter is smooth and homogenous.
              
              
              
                06 - 
                Fold in 70 g sweetened shredded coconut until evenly distributed.
              
              
              
                07 - 
                Evenly spread batter into the prepared sheet pan and bake for 18–20 minutes, or until a toothpick inserted in the center emerges clean.
              
              
              
                08 - 
                While the cake bakes, melt 113 g unsalted butter with 60 ml milk in a medium saucepan over medium heat.
              
              
              
                09 - 
                Remove pan from heat; gradually whisk in 360 g powdered sugar and 1 teaspoon vanilla extract until smooth.
              
              
              
                10 - 
                Fold in 70 g sweetened shredded coconut to the frosting.
              
              
              
                11 - 
                When cake is baked, let it cool briefly, then spread frosting evenly over the warm surface.
              
              
              
                12 - 
                Allow cake to cool completely before cutting into squares for serving.