Heat oven to 425 degrees. Spray a baking sheet lightly with oil.
Slice each mini bagel in half and set on baking sheet. Scoop about 1 tbsp marinara sauce atop each half. Top with a pinch of each type of cheese (about 1/2 tbsp each, but I just eyeball it) until all cheese is used up.
Bake 10 minutes, then turn the broiler to high and cook 2-3 minutes more until cheese begins to brown. Serve garnished with a sprinkle of fresh parsley.