Preheat oven to 190 degrees C. Grease a 20x30cm baking dish.
In a large saucepan over medium heat, cook and stir zucchini and lemon juice until zucchini is tender, 15 to 20 minutes. Stir in 1 cup sugar, 1 teaspoon cinnamon and nutmeg and cook one minute more. Remove from heat and set aside.
In a large bowl, combine flour and 2 cups sugar. Cut in butter with pastry blender or two knives until mixture resembles coarse crumbs. Stir 1/2 cup of butter mixture into zucchini mixture.
Press half of remaining butter mixture into bottom of prepared pan. Spread zucchini mixture over top of crust, and sprinkle remaining butter mixture over zucchini. Sprinkle with 1 teaspoon cinnamon.
Bake 35 to 40 minutes, or until top is golden. Serve warm or cold.