Step 1: Prepare the Cake Batter

Preheat your oven to 350°F (175°C).

Grease and lightly flour two 9-inch round cake pans.

In a large bowl, combine cake mix, buttermilk, vegetable oil, egg whites, and vanilla extract.

Beat with an electric mixer on medium speed for 2 minutes, or until smooth.

Bake the Cake

Divide batter evenly between the two prepared pans.

Bake for 25–30 minutes, or until a toothpick inserted in the center comes out clean.

Let cakes cool in pans for 10 minutes, then remove and cool completely on a wire rack.

Make the Coconut-Pecan Frosting

In a medium saucepan over medium heat, melt the butter.

Stir in sugar, evaporated milk, egg yolks, and vanilla extract.

Cook, stirring constantly, for 10–12 minutes, or until the mixture thickens and turns golden brown.

Remove from heat. Stir in shredded coconut and chopped pecans.

Allow frosting to cool slightly before using.

Assemble the Cake

Place one cake layer on a serving platter. Spread half of the coconut-pecan frosting over the top.

Place second cake layer on top and spread the remaining frosting over the top and sides.

Let the cake rest for 15 minutes before slicing to allow frosting to set.