Combine eggs in a medium mixing bowl; beat until thick and lemon colored at medium speed of an electric mixer. Gradually add sugar, beating until smooth. Add flour, soda, pineapple, and vanilla; beat well. Stir in 1/2 cup chopped pecans.
Pour batter into a wellgreased 13- x 9- x 2-inch glass baking dish. Bake at 325° for 40 minutes or until a wooden pick inserted in center comes out clean. Cool in baking dish 10 minutes; remove from dish, and cool completely. Spread frosting on top and sides of cake. Garnish top with 1 1/2 cups coarsely chopped pecans. Cut into squares to serve.