Peel the zucchini. Then cut them in half long-ways and use a spoon to scrape out the seeds. Make sure to get all of them.
Slice the zucchini into 1/4" thick slices.
In a large pot, combine the sliced zucchini, cinnamon, sugar, lemon juice, and water and bring to a boil.
Boil for 15 minutes. Preheat the oven to 375°F
While the zucchini boils, make the topping.
Mix the oatmeal, cinnamon, brown sugar, flour and butter together in a bowl using a fork.
When the zucchini is done boiling, pur it into a greased 9x13 baking pan.
Top the zucchini with the topping mixture. Use your fingers to sprinkle the topping evenly over the surface.
Bake uncovered for 55-60 minutes at 375°F. The edges will just look golden brown when it's ready to come out.
Serve warm with vanilla ice cream.