Combine the diced zucchini, fresh lemon juice, lemon zest, and grated ginger root in a large skillet. Place the skillet on a burner set to medium-low. Cook the zucchini for 15-20 minutes, stirring every minute or two, until it is tender and has released some of its water. Once the zucchini reaches this point, add the cinnamon, vanilla, and sugar. Stir to combine, then cook for only 1 more minute before removing the zucchini mixture from the burner. The mixture will look like it has a lot of liquid now thanks to the addition of the sugar but this is fine! It will caramelize and thicken in the oven. Set this mixture aside to cool while you prepare the other ingredients.

Preheat your oven to 350 degrees. In a medium-sized bowl, stir together the rolled oats, flour, and sea salt. Add the butter and use either a fork or your fingers to begin mashing it into the dry ingredients. Once the butter has broken down into smaller pieces (pea-sized or smaller) and the mixture looks crumbly, stir in the maple syrup or honey. The crumble mixture should hold together in a ball when you squeeze it in your hand.

Pour the zucchini mixture into a quart-sized baking dish (I used a pie dish). Spread it into an even layer, then scatter the crumble mixture over the top into an even layer. Bake the crumble in your preheated oven for 35-40 minutes or until the crumble topping is golden and you can see the juices bubbling up around the edges. Cool for at least 15 minutes before serving.