Preheat your oven to 450 degrees Fahrenheit.
Place the bell peppers on a baking sheet lined with parchment paper and roast them at 450 degrees for 30 minutes, turning them over at about the 15-minute mark.
Remove peppers from the oven and cut them open so they cool quickly. You should be able to peel the skin off easily and the stem and seeds should also be easy to remove. Once they're cool enough to handle, chop the peppers and set them aside.
Turn your oven down to 350 degrees Fahrenheit and let it reach the correct temperature while you assemble the quiches.
Stack 4 large phyllo pastry sheets one on top of the other. Cut the phyllo pastry (4 sheets thick) into 12 squares.
Spray a 12-cup muffin tin with cooking spray and arrange the phyllo squares in each muffin cup, offsetting the corners to create a flower-petal effect.
Add the eggs, milk, salt and pepper to a bowl and whisk until combined.
Distribute half the chopped roasted red peppers evenly between each of the 12 muffin cups. Sprinkle half of the shredded cheese and all the green onions overtop of the roasted red peppers. Pour the egg mixture evenly into the 12 muffin cups and top with the remaining chopped roasted red pepper and the remaining shredded cheese (layering the ingredients like this helps create a nice presentation with a little bit of red peeking through the top of the egg mixture once they're baked).
Bake immediately for about 18 minutes at 350 degrees Fahrenheit, or until the egg is set and the phyllo just starts to turn a light golden brown colour.
Garnish with a few chopped green onions and serve immediately while they're warm and the phyllo is crispy!