Whisk together eggs, milk, salt, garlic powder, and pepper.
Heat 1 tsp. of olive oil in a large nonstick skillet. Add spinach and cook stirring often, until it begins to wilt. Pour in eggs and cook, just until set, about 3 minutes.
To make the quesadillas: Sprinkle tortilla with half of the shredded cheese. Spoon the egg mixture on top, then place the other tortilla on top.
Carefully wipe out skillet and heat olive oil. Cook quesadillas on both sides until golden, about 5-6 minutes. Cut into triangles and serve.