Eggs act as a binder for the crust. If you are completely vegetarian and prefer to skip eggs, use about a teaspoon of cream cheese and flour. Another trick is to spread your cheese and then comes the marinara sauce. As the cheese will melt and adhere to the base while baking.
If vegan use dry flour of your choice like almond, all purpose or cornflour as your binder and use sparingly as required if your cauliflower is very moist. Alternatively, if the crust mix is too dry to break apart, then mix the flour with some water to make it a paste like consistency.
Add your favorite toppings and the options are endless so feel free. I missed pineapple chunks, anchovies and artichokes. Marinara sauce tastes better if homemade. I make mine using both fresh and canned tomato paste for consistency, flavor and rich color.
I also prefer to line my pan with aluminium foil (greased) as it's easy to lift off the pan and cleaning is a breeze. Let's stay home safe, bake healthy food to hog well!