• For the Cake:
• Preheat your oven to 350°F (175°C). Prepare three 8-inch round cake pans by lining the bottoms with parchment paper and lightly greasing the sides. If you prefer, you can also use bake-even strips for more level layers.
• In a large mixing bowl, combine the granulated sugar, vegetable oil, melted butter, eggs, egg whites, and sour cream. Beat the mixture on medium speed for about 2 minutes, until the batter is smooth, lighter in color, and well combined. Be sure to scrape down the sides of the bowl to ensure everything is incorporated evenly.
• In a separate bowl, whisk together the flour, baking powder, baking soda, and salt. Begin alternating additions of the dry ingredients with the coconut extract, vanilla extract, and coconut milk. Start by adding half of the dry mixture, followed by half the coconut milk and extracts, then repeat with the remaining halves. Mix until just combined—avoid overmixing. Use a spatula to scrape the bowl’s sides and bottom, folding the batter to ensure it's fully incorporated.
• Evenly divide the batter among the three prepared pans, pouring about 1 2/3 cups of batter into each. Bake for 20–24 minutes, rotating the pans halfway through to ensure even baking. The cakes are ready when a toothpick inserted into the center comes out clean. Remove them from the oven and let them cool completely on a wire rack before assembling.
• To toast the coconut for decorating, use the same preheated oven. Spread the shredded coconut evenly on a parchment-lined baking sheet. Bake for 5–8 minutes or until golden brown, watching closely to prevent burning. Once toasted to your liking, transfer the coconut to a bowl or plate to cool and stop the cooking process.

For the Filling:

• In a small bowl, whisk together 3 tablespoons of the heavy whipping cream and the cornstarch until the mixture is smooth and thickened slightly. If it's too thick, add a bit more cream to loosen it into a liquid consistency.
• In a medium saucepan over medium heat, melt the unsalted butter. Add the remaining heavy whipping cream, granulated sugar, and shredded sweetened coconut. Cook the mixture, stirring occasionally, until it just begins to bubble and is nearly boiling.
• Add the prepared cornstarch slurry to the saucepan, stirring constantly. Continue to cook the filling over medium-high heat until it thickens, making sure to stir continuously to prevent burning. Once thickened, whisk in the vanilla extract. Remove from heat and allow the filling to cool completely before using.

For the Frosting:

• Once the cake layers and filling have fully cooled, prepare the cream cheese frosting. In a large mixing bowl fitted with a paddle attachment, combine the softened butter and cream cheese. Beat on medium-high speed until the mixture is smooth, creamy, and well blended.
• Gradually add the powdered sugar, one cup at a time, beating until each addition is fully incorporated. As the frosting thickens, add the vanilla extract and beat to combine. Mix until the frosting is smooth and spreadable.

To Assemble the Cake:

• Evenly divide the coconut filling into two portions. Place the first cake layer onto an 8- or 10-inch cake board or serving plate. Using a large round piping tip, pipe a ring or “dam” of frosting around the edge of the layer to contain the filling.
• Spoon one half of the coconut filling into the center and gently spread it out evenly within the dam. Place the second cake layer on top and repeat the process with the second half of the filling and another dam of frosting. Top with the third cake layer.
• Using the prepared cream cheese frosting, cover the top and sides of the assembled cake. A thinner layer is fine, as the toasted coconut will add texture and coverage.
• Take the cooled, toasted shredded coconut and gently press it into the frosting on all sides of the cake, making sure to cover it thoroughly.
• Refrigerate the cake for at least 30 minutes before serving to allow the filling and frosting to set. Store the finished cake in an airtight container in the refrigerator to keep it fresh and prevent it from drying out.