Pour boiling water over oats; let stand 20 minutes.
Cream 1/4 cup butter; gradually add 1 cup brown sugar and 1 cup sugar, beating well. Stir in oats mixture. Add next 6 ingredients, and mix well. Spoon mixture into a greased 13- x 9- x 2-inch baking pan. Bake at 350° for 40 minutes or until a wooden pick inserted in center comes out clean.
Combine coconut and pecans; sprinkle mixture over cake. Combine remaining ingredients, and pour over cake. Return cake to oven, and broil 2 minutes or until golden brown. Cut into squares to serve.