Preheat oven to 275-degrees F.
Lightly coat a 13x9 pan with nonstick cooking spray & set aside. Place cereal in plastic bag & seal. Using a rolling pin, crush the cereal to fine crumbs. Open the bag and measure crumbs to 1/2 Cup. Combine crumbs with 1 Cup of Flour in mixing bowl. Add 1/3 Cup brown sugar & stir to blend. Blend the softened butter into the dry ingredients until well combined. Transfer to baking pan and press into pan, making an even layer. Bake in preheated oven about 10 minutes or until Golden. Remove from oven & set aside.
Increase oven temp to 350-degrees F.
Combine the remaining 2-Tblspn of flour with salt & set aside. Combine eggs, remaining brown sugar, & vanilla in bowl. Beat until well blended. Beat in coconut. Add the reserved flour/salt mixture & nuts and mix well. Spoon mixture into the crust-filled pan, spreading out with rubber spatula to cover evenly. Bake in preheated oven for about 20 mins or until lightly browned & set.
Remove from oven and set aside to cool slightly. While bars are still warm, pour on the lemon icing, spreading it out with a rubber spatula to make an even layer of icing. Set aside to cool completely. When cool, cut into 36 bars.
TO MAKE ICING: Combine Sugar with butter and Lemon juice in small bowl, beating until smooth.