Preheat your oven to 350°F (175°C). Grease and flour three 8-inch round cake pans.

In a medium bowl, whisk together the flour, baking powder, baking soda, and salt until evenly combined.

In a large mixing bowl, cream the softened butter and granulated sugar together until light and fluffy, about 5 minutes.

Add the eggs one at a time, beating well after each addition. Then add the sour cream, vanilla extract, and coconut extract, mixing until combined.

Gradually add the flour mixture, alternating with the milk, starting and ending with the flour. Mix until just combined.

Divide the batter evenly among the prepared pans and bake for 25-28 minutes, or until a toothpick comes out clean.

Allow the cakes to cool in the pans for about 10 minutes, then transfer to wire racks to cool completely.

In a medium bowl, mix the sour cream, granulated sugar, and shredded coconut for the filling, then refrigerate.

In another bowl, whisk together the sour cream, powdered sugar, and vanilla extract for the frosting until smooth. Fold in the whipped topping.

Once the cake layers are cool, level them if necessary. Spread half of the coconut filling between the first two layers.

Place the third layer on top, then frost the top and sides of the cake with the sour cream frosting. Press toasted coconut onto the sides and sprinkle more on top.