Preheat oven to 350°F. Grease 13x9x2-inch baking pan; set aside.
In large bowl, combine flour, sugar and baking soda. Stir in undrained crushed pineapple, eggs and 1 teaspoon of the coconut extract until just combined (do not overmix). Stir in walnuts. Spread batter into prepared pan. Bake 30 to 35 minutes or until golden brown and toothpick inserted in center comes out clean. Cool in pan on wire rack 30 minutes.
In medium mixing bowl, beat cream cheese, butter and remaining 1 teaspoon of the extract with an electric mixer on medium speed until fluffy. Gradually beat in powdered sugar. Spread over warm cake. Cool completely. Cover and chill.