Bake cake mix in 9x13 pan according to instructions on box and let cool for 15 minutes. Poke holes in cake 1/2" apart. Pour 1 can of Eagle brand condensed milk on cake and let stand until absorbed. Pour 14 oz jar of Caramel, Butterscotch, or Fudge topping on top of cake. Cover and refrigerate for 2 hours. Top with Cool Whip and chopped pecans.
Combine evaporated milk, sugar, egg yolks, butter, and vanilla. Cook & stir over medium heat until thickened, about 12 minutes. Add coconut flakes and chopped pecans. Beat until thickened enough to spread. Makes about 2 cups, enough for a sheet cake.