Stir cocoa and baking soda in mixing bowl, blend in half of the oil, add boiling water; stir until mixture thickens. Stir in sugar, eggs, remaining oil, stir until smooth. Add flour, mintflavoring and salt, blend very well together. Pour into lightly greased 13 X 9 inch baking pan or two 8 inch sqare pans. Bake at 350 degress F for 35 to 40 minutes for big pan, about 30-32 minutes for two small pans.While the brownies are still hot, arrange the cream filled mint patties on top, bake another 3 minutes than spread all evenly around. Let cool, cut into squares.