Position an oven rack in the center and preheat to 375°F. Lightly oil or spray a 9-inch pie dish so the tortilla won’t stick.
Press the flour tortilla into the prepared pie dish, tucking and pleating the edges so it forms a shallow crust. Trim any extreme overhang so the edges are neat.
To help the shell crisp, place the lined dish on a baking sheet and bake the empty tortilla for 3–4 minutes until it just begins to set and the edges start to firm. Remove from oven and lower oven temperature to 350°F.
Meanwhile, combine the eggs, liquid egg whites and cottage cheese in a medium bowl. Use a fork or small whisk and mash the cottage cheese into the eggs so the mixture is smooth and slightly frothy. Stir in salt, pepper and smoked paprika.
Scatter the chopped spinach and diced red pepper evenly across the pre-baked tortilla shell. Pour the egg-and-cheese mixture over the vegetables, then finish with the shredded cheese on top.
Return the pie dish to the oven and bake at 350°F for 18–20 minutes, or until the filling is set in the center (a knife inserted in the middle should come out mostly clean) and the top is lightly golden.
Allow the quiche to rest on a wire rack for 8–10 minutes before cutting — this firms the filling and makes slicing cleaner. Serve warm or at room temperature.