Preheat your oven to 325 degrees F. Spray a 12-cup bundt pan with nonstick spray. Dust with granulated sugar. Set aside.
In a medium size bowl, whisk together flour, baking powder, and salt. Set aside.
In a small mixing bowl, stir together the coconut milk, buttermilk, and coconut emulsion. Set aside.
In the bowl of a stand mixer fitted with the paddle attachment, beat the butter and sugar on medium speed until light in color and fluffy in texture, about 2 to 3 minutes.
Stir in the melted white chocolate, followed by the eggs and egg whites, making sure to scrape down the sides and bottom of the bowl in between additions.
Continue to beat on medium-high speed for about 2 minutes, until the mixture gets smooth in texture and slightly bigger in volume.
With the mixer on low speed, add ⅓ of the flour mixture, followed by ½ the coconut mixture, another ⅓ of the flour, the second ½ of the coconut mixture, and then the remaining flour mixture. Stir until just combined.
Pour the batter into the prepared pan. Sprinkle the top of the cake (which turns into the bottom) with the toasted coconut and then cover with the toffee bits (the coconut flakes need to go first so you can cover them with the toffee to help prevent the flakes from browning too much). Bake for 50 to 55 minutes, or until a toothpick inserted in the center of the cake comes out with a few moist crumbs on it.
Remove from oven and place the bundt pan on a cooling rack to cool completely. Allow the cake to cool for about an hour, until it’s room temperature, before inverting the cake on a cake stand. Allowing the cake to cool completely in the pan helps the cake to release from the sides cleanly when it’s time to take the cake out.
In the bowl of a stand mixer fitted with a paddle attachment, beat the butter and cream cheese for about 2 minutes, until lighter in color and fluffier in texture.
With the mixer on low, gradually add the sifted powdered sugar, one cup at a time, mixing a little in between each addition.
Stir in the coconut emulsion and salt.
Turn the mixer to medium-high speed and beat for an additional 3 to 5 minutes. The buttercream will become lighter in color and texture.
Spread or pipe the buttercream on top of the cake. Cover with shredded coconut.