Start by preparing your fathead dough base. Add the coconut flour, 3/4 cup of grated cheddar, the mozzarella, cream cheese, half a teaspoon of salt, black pepper, onion powder, butter and parmesan to a food processor. Blend well to combine until you have a chunky crumb consistency.
Crack the eggs into the food processor. Blend again until well combined and a dough forms in the food processor. The dough should be only slightly tacky and easy to mold.
Preheat the oven to 375 degrees Fahrenheit. Cut two large squares of baking paper. Turn the dough out onto one of the baking paper squares. Cover with the remaining sheet of paper and roll into a circle about 1/4 inch thick. The pizza base will be roughly the size of a dinner plate. You can use a plate as a template if you wish to score your dough circle.
Carefully lift the pizza base on the bottom sheet of paper onto a large shallow baking tray. Transfer to the oven. Bake for 10 minutes until lightly golden and starting to firm. Whilst the pizza base is cooking you can prepare your toppings. Heat a tablespoon of olive oil in a skillet over a medium heat. Add the ground pork and cook until well browned all over. Remove from the pan with a slotted spoon and set to one side.
After 10 minutes, remove the pizza base from the oven to add the toppings. Spoon the passata in an even layer over the pizza base and sprinkle over the remaining grated cheddar. Thinly slice the tomatoes and mushrooms and arrange over the pizza. Crumble over the ground pork. Season everything with a little salt and sprinkle over the oregano. Drizzle with the remaining olive oil.
Return the pizza to the oven. Cook for a further 12-15 minutes or until the pizza base is golden, the pork is crisp and the cheese is melted. Serve hot as is, or with a side salad.