Grease a 13x9x2-inch baking pan. Set aside.
In a large bowl, beat the 1/2 cup butter with an electric mixer on medium speed for 30 seconds.
Beat in the 1-1/2 cups granulated sugar until well combined. Add eggs and beat well. Stir in flour and baking soda. Add undrained pineapple. Beat well.
Spread in prepared baking pan. Sprinkle with brown sugar and walnuts or pecans.
Bake in a 375 degree F oven for 35 to 40 minutes or until a toothpick inserted near the center comes out clean.
Meanwhile, for the topping, in a small saucepan, stir together the 3/4 cup granulated sugar and the cornstarch; add milk and the 1/2 cup butter. Cook and stir until thickened and bubbly; cook and stir for 2 minutes more. Stir in vanilla.
Cool cake and topping for 15 minutes. Spread topping over cake. Sprinkle with almonds. Cool completely. Makes 15 servings.