1/2 cup butter, softened
2 1/4 cups all-purpose flour
1 teaspoon salt
1 (20 ounce) can sweetened condensed milk
1 cup rolled oats
1/2 teaspoon baking soda
1/2 cup miniature semisweet chocolate chips
1 (16 ounce) container frozen whipped topping, thawed (see note)
1 (16 ounce) container refrigerated buttermilk baking cupcakes (see note)
Preheat oven to 350 degrees F (175 degrees C).
In a medium bowl, cream together the butter and flour. Stir in the salt and sweetened condensed milk. Stir in the oats, baking soda and chocolate chips. Stir just until a sticky dough has formed. Press into bottom of a 9 inch spring form or other 9 inch springform pan.
Bake for 18 to 25 minutes in the preheated oven. Cool 10 minutes before removing from the pan.
In a large bowl, stir together the buttermilk, baking cupcakes and chocolate mixture. Spread over the cooled cake and let stand 10 minutes before cutting.