Preheat the oven to 350 degrees. Prepare your round cake pans. For this recipe, it yields two 8" rounds or two 9" rounds. Line the bottom of the cake pans with parchment paper and set aside.
In your standing mixer, or using a large bowl with a hand electric mixer, you are going to combine together softened butter and coconut sugar. I prefer using the paddle attachment. Beat together until fluffy and light.
In a large mixing bowl, whisk to combine the egg yolks, whole milk, sour cream and vanilla. Add these ingredients to the butter and sugar mixture while the mixer at a low speed. Mix to combine.
Add to the standing mixer flour mixture, baking powder, baking soda and salt. Still using the paddle attachment and at a low speed until incorporated, then increase to medium speed for 1 minute. Turn off the mixer.
Fold into the batter chopped pecans and shredded (unsweetened) coconut.
I will typically use my hand mixer and a medium bowl to do this, since the cake batter is taking up the standing mixer bowl. Using my hand mixer with the whisk attachment, at high speed I will whip the egg whites until they are stiff peaks - about 2 to 3 minutes. Fold the egg whites into the cake batter - I am telling you, this step is crucial for a beautiful cake texture!
Pour batter into the prepared cake pans, and pop into the oven to bake for 25 minutes. I always check my cake at the 20 minute mark. If you touch the top of the cake and it bounces back up, it is ready! Let the cake cool for 5 minutes before turning it onto a cooling rack.