In saucepan combine 2/3 cup of the butterscotch pieces with 1/4 cup water. (Reserve remaining pieces for filling.)
Heat and stir till pieces melt; set aside.
In mixing bowl cream together sugar and butter till fluffy.
Add eggs one at a time; beat well after each.
Beat in butterscotch mixture.
Combine flour, baking powder, soda, and salt.
Add to creamed mixture alternately with buttermilk, beating just till blended after each addition.
Pour into 2 greased and floured 9x1 1/2 inch round baking pans.
Bake at 375° for 25 to 30 minutes; cool.
Assemble cake layers with Coconut Pecan Filling.
Before serving, whip cream; frost sides of cake.
Coconut Pecan Filling: In saucepan blend 1/2 cup sugar and 1 tablespoon cornstarch.
Stir in one 5 1/3 ounce can evaporated milk (2/3 cup).
Cook and stir over medium heat till thickened and bubbly.
Remove from heat.
Stir in reserved butterscotch pieces and 2 tablespoons butter or margarine.
Add 1 cup flaked coconut and 1/2 cup chopped pecans.
Spread half atop each layer.