First, let's start with the crumble mixture. In a large mixing bowl, combine the flour, yeast, salt, and parmesan cheese. Mix it together a bit so everything is combined, then add in the butter in small pieces.
Work the mixture together with your hands until decently mixed together, then add the egg and continue working the mixture with your hands until it starts to gain a crumbly texture. Set aside in the fridge while you prepare the next part!
Cut up the zucchini into fourths and start heating up a large frying pan on medium heat; once it’s hot, drizzle in some olive oil and add the zucchini. Cook for about 6-7 minutes, stirring occasionally, or until they are fully cooked. Season with salt and pepper, transfer to a bowl, and set aside until cooled. Once they are cooled, gently mix in the ricotta cheese and set aside.
Lightly oil a round mold and place parchment paper on the bottom (cut it out so it lines the bottom without any overlap on the sides). Use about half of the crumble mixture to coat the bottom and edges of the mold and, with a spoon, gently pack down and flatten out (don’t pack too hard though, it might affect cooking times).
Scoop in the zucchini ricotta mixture on top of the packed down crumble base and level out then add a layer of ham on top. Cover the ham layer with the last of the crumble mixture until it’s all coated.
Bake in the oven at 355° for about 50-55 minutes on the bottom rack. Let cool for a few minutes before you slice it up and serve!