Preheat oven to 375 degrees F (190 degrees C). Coat a 9x13 inch baking dish with cooking spray.
Place zucchini and lemon juice in a medium saucepan. Cook, covered, over medium-low heat, stirring occasionally, for about 15 minutes, or until tender. Stir in 3/4 cup sugar, 1 teaspoon cinnamon, and nutmeg. Simmer 1 minute longer, remove from heat, and set aside.
In a large mixing bowl, combine flour and 1 1/2 cups sugar.
Cut in butter until the mixture resembles coarse crumbs. Stir 1/2 cup crumb mixture into zucchini mixture. Press half the remaining crumb mixture into the prepared pan.
Spread zucchini evenly over crust. Crumble remaining crumb mixture over zucchini, and sprinkle with 1 teaspoon cinnamon.
Bake in the preheated oven for 35 to 40 minutes, or until golden and bubbly.