Grease and flour the bottoms of three 9 inch layer pans. Preheat oven to 350 degrees F (175 degrees C).
Melt 1/4 cup butter or margarine in a heavy skillet over medium heat. Add pecans, and brown for 10 to 15 minutes, stirring frequently.
Cream 1 cup butter or margarine in large mixing bowl. Gradually add 2 cups white sugar, and cream until light and fluffy with mixer on high speed. Blend in eggs one at a time, beating well on medium speed after each addition. Sift together flour, baking powder, and 1/2 teaspoon salt. At low speed add sifted ingredients alternately with milk and vanilla extract, beginning and ending with dry ingredients. Blend well after each addition. Stir in 1 1/3 cups of the toasted pecans. Pour batter into pans.
Bake at 350 degrees F (175 degrees C) for 25 to 30 minutes, until cake is golden brown and springs back when lightly touched in center.
To Make Frosting: Cream 1/4 cup butter in mixing bowl. Add 1 teaspoon vanilla extract, 1/4 teaspoon salt, confectioners' sugar and cream. Beat until smooth and of spreading consistency. If necessary, thin with additional cream. Blend remaining 2/3 cup pecans into frosting. Fill and frost the cake.