Preheat oven to 350°F (175°C). Grease and flour two 9-inch round cake pans (or three 8-inch pans). Line bottoms with parchment paper.

In a medium bowl, whisk together sifted all-purpose flour, baking powder, baking soda, and salt. Set aside.

In a large bowl, cream together softened unsalted butter and granulated sugar with an electric mixer until light and fluffy (3-5 minutes).

Add large eggs one at a time, beating well after each addition. Stir in vanilla extract.

In a separate bowl, whisk together full-fat canned coconut milk and sour cream.

Gradually add the dry ingredients to the wet ingredients in three additions, alternating with the coconut milk mixture, beginning and ending with dry ingredients. Mix on low speed until just combined. Do not overmix.

Fold in 1 cup of sweetened shredded coconut.

Divide batter evenly between prepared cake pans. Bake for 30-35 minutes, or until a wooden skewer inserted into the center comes out clean.

Let cakes cool in pans for 10-15 minutes before inverting onto a wire rack to cool completely.

In a medium saucepan, whisk together 1.5 cups full-fat canned coconut milk, 1/2 cup granulated sugar, and cornstarch until smooth.

Cook over medium heat, whisking constantly, until the mixture thickens and comes to a boil. Boil for 1 minute, then remove from heat.

In a small bowl, whisk large egg yolks. Gradually temper the hot coconut mixture into the egg yolks by slowly adding about 1/2 cup of the hot mixture to the yolks while whisking vigorously.

Pour the egg yolk mixture back into the saucepan with the remaining hot coconut mixture. Return to medium heat and cook, whisking constantly, for 1-2 minutes until very thick. Do not boil.

Remove from heat. Stir in cold unsalted butter, vanilla extract, and optional coconut extract until butter is melted and incorporated.

Transfer filling to a clean bowl, cover the surface directly with plastic wrap to prevent a skin from forming, and chill in the refrigerator for at least 2 hours, or until completely cold and firm.

In a large bowl, beat softened cream cheese and softened unsalted butter with an electric mixer until smooth and creamy.

Gradually add sifted powdered sugar, 1 cup at a time, mixing on low speed until incorporated, then increasing speed to medium.

Beat in vanilla extract and coconut extract.

If frosting is too thick, add heavy cream 1 tablespoon at a time until desired spreadable consistency is reached. Beat until light and fluffy.

If desired, level the cake layers with a serrated knife if they have domed tops.

Place one cake layer on a serving plate or cake stand. Spread about half of the chilled coconut cream filling evenly over the top, leaving a small border.

Carefully place the second cake layer on top. Spread the remaining coconut cream filling.

Place the third cake layer (if using three layers) or the final layer on top.

Crumb coat the entire cake with a thin layer of the cream cheese coconut frosting to seal in any loose crumbs. Chill for 15-20 minutes.

Apply the remaining cream cheese coconut frosting to the top and sides of the cake, using an offset spatula to create smooth or decorative swirls.

To toast shredded coconut: Spread 1.5 cups sweetened shredded coconut in a single layer on a baking sheet. Bake at 325°F (160°C) for 5-10 minutes, stirring occasionally, until golden brown. Watch carefully as it can burn quickly. Let cool completely.

Press the cooled toasted shredded coconut onto the sides and top of the frosted cake.

Refrigerate the cake for at least 1 hour before slicing to allow the filling and frosting to set.