Preheat oven to 350 degrees and lightly spray a 9x13 pan with non-stick spray. Set aside.
Combine softened butter and both sugars in a bowl and beat until well combined. I used a hand mixer but you can mix it by hand or with a stand mixer. Add eggs and stir well after each. Add shredded zucchini, vanilla and sour cream, mix to combine.
Add flour, baking powder, salt and stir until just combined {don't over mix}. Pour into the bottom of the greased 9x13 pan.
In a small bowl combine all of the crumb mixture ingredients. Work the mixture together into small crumbs using a fork. Don't over work the mixture or you will get a paste and it will change the texture of the bread. Sprinkle the crumbs in an even and thick layer over the top of the zucchini bread batter.
Bake for 30-35 minutes or until a toothpick inserted in the center comes out with only a few moist crumbs or is clean.
Serve your zucchini crumb cake either warm or cool and cover. Store at room temperature for up to 3 days.