To make corn flour (cornstarch) slurry, combine together corn flour (cornstarch) and water.
Heat butter in a large frying pan or skillet over medium heat-high heat.
Add garlic. Sauté, stirring, for one minute or until fragrant.
Add corn and spinach. Sauté, stirring occasionally, for about 2-3 minutes or until the vegetables are cooked.
Add milk and corn flour (cornstarch) slurry. Stir to combine. Cook for about 2-3 minutes.
When the sauce thickens, add red chili flakes and dried oregano. Season with salt and pepper. Stir. Simmer for about 3 minutes.
Add grated mozzarella. Stir. Cook for a minute or until the cheese melts.