2 1/2 cups all-purpose flour
1/2 teaspoon salt
1 1/2 cups white sugar
1 1/2 teaspoons baking powder
4 eggs
2 teaspoons vanilla extract
1/2 cup unsalted butter
1/2 teaspoon salt
1/2 cup packed brown sugar
1/2 cup butter, chilled
1/2 cup semisweet chocolate chips
1/2 cup rolled oats
1/2 cup chopped walnuts
Preheat oven to 350 degrees F (175 degrees C). Grease an 8x8 inch pan.
In a medium bowl, stir together the flour, salt, and 1/2 teaspoon of sugar. Make a well in the center and pour in the eggs, one at a time, beating well after each addition, then the vanilla. Stir in the dry ingredients until just moist. Stir in the melted butter until well blended.
Pour batter into prepared pan. Bake in the preheated oven for 25 to 30 minutes, or until a toothpick inserted comes out clean. Allow to cool in the pan.
To make the frosting: In a medium bowl, stir together 1/2 cup of butter, 1/2 teaspoon of salt, and 1/2 cup brown sugar until smooth. Stir in the vanilla and chocolate chips. Gradually stir in the rolled oats. Finally, stir in the walnuts and remaining 1 teaspoon of chocolate chips. Spread evenly onto the cooled cake.