Beat eggs; add oranges and dry ingredients. Beat 4 minutes with electric mixer on slow speed until oranges flake through the batter. Pour into greased 13 x 9-inch cake pan.
Bake at 350 degrees F for 35 to 40 minutes. Cake will get quite dark.
Before removing from oven, press top with fingertip to see if it bounces back. If it doesn't, bake a bit longer, taking care it doesn't burn.
Remove cake from oven. Pour topping over.
Return cake to oven and bake 5 minutes longer.
Combine Topping ingredients and bring to a rolling boil.