Preheat the oven to 350 degrees.

Work with 4 sheet of filo at a time (and keep the unused filo sheets covered with plastic wrap and a damp towel). Place one sheet of filo on a clean, flat surface (I used a parchment-lined baking sheet). Spray the filo with cooking spray or brush gently with olive oil. Arrange a second sheet on top and spray with cooking spray or brush gently with olive oil. Repeat 2 more times, creating a stack of 4 sheets. Divide the stack into 6 equal squares. Press the squares into the bottom and up the sides of a 12-cup muffin pan. Repeat with the remaining 4 sheets of filo, creating six more cups. You will now have 12 cups ready to fill. Set aside.

Heat the oil in a large skillet over medium-high heat. Add the onion and cook for 3 minutes, until soft. Add the corn and garlic and cook for 1 to 2 minutes, until the garlic is fragrant. Remove the pan from the heat.

In a medium bowl, whisk together the eggs, milk, dried parsley, 1/2 teaspoon salt, and 1/4 teaspoon black pepper.

Spoon the corn mixture into the filo cups, distributing the mixture evenly. Top the corn mixture with the cheddar cheese. Spoon the egg mixture over top, distributing the mixture evenly.

Bake for 25 to 30 minutes, until the filo is golden brown and the egg mixture is set. Cool for 5 minutes. Top with parsley (if using) and serve.