Preheat the oven to 325 degrees F.
Coat a 12-cup fluted tube pan with nonstick baking spray.
Using the extra granulated sugar, dust the greased tube pan.
In a medium bowl, add the flour, the baking powder, and 1 teaspoon of the salt and whisk to combine.
In a small mixing bowl, add the coconut milk, the buttermilk, and 1 tablespoon of the coconut extract and stir to combine. Set the coconut mixture aside.
In the bowl of a stand mixer fitted with the paddle attachment, add 2 sticks of the room temperature butter and 1 3/4 cups of the remaining granulated sugar and beat on medium speed until it is combined, light in color, and fluffy, about 2-3 minutes.
Add the melted white chocolate to the butter mixture and stir to combine, while scraping down the sides and the bottom of the bowl.
Add the eggs and the egg whites to the butter mixture and stir to combine, while scraping down the sides and the bottom of the bowl.
Beat the butter mixture on medium-high speed until it is smooth in texture and slightly larger in volume.
Reduce the mixing speed to low.
Add 1/3 of the flour mixture to the butter mixture and beat until just combined.
Add 1/2 of the coconut mixture to the butter mixture and beat until just combined.
Add 1/2 of the remaining flour mixture and the remaining coconut mixture to the butter mixture.
Add the remaining flour mixture to the butter mixture and stir until just combined into a batter. Do not overmix.
In the prepared fluted tube pan, add the batter and spread it out evenly.
Sprinkle batter with the toasted shredded coconut and then the toffee bits. It is essentially to sprinkle the coconut and the toffee bits in this order in order to prevent the coconut from browning too much.
Bake until a toothpick inserted into the center of the cake comes out with only a few moist crumbs attached, about 50-55 minutes.
Transfer the cake to a cooling rack to cool completely, about 1 hour.
Invert the cake onto a cake stand or serving plate.
In the clean bowl of a stand mixer fitted with a clean paddle attachment, add the remaining slightly cold butter and the cream cheese and beat until it is combined, lighter in color, and fluffier in texture, about 2 minutes.
Reduce the mixing speed to low.
Gradually add the sifted powdered sugar to the cream cheese mixture, 1 cup at a time, and mix a little after each addition, until it is all incorporated.
Add the remaining coconut extract and the extra salt to the butter mixture and stir until it is combined and a frosting begins to form.
Increase the mixing speed to medium-high and beat until the frosting is lighter in color and texture, about 3-5 minutes.
Spread or pipe the frosting on top of the cake.
Cover the frosting with the sweetened shredded coconut.
Serve.