Bring a large pot of salted water to a boil and add your spinach pasta. Cook according to the package directions until just tender, usually around 8 to 10 minutes. Drain it in a colander and toss with a little olive oil so it doesn't stick together while you prep the eyeballs.
While the pasta cooks, pour your marinara or pasta sauce into a small saucepan over medium-low heat. Stir occasionally so it warms through evenly without sticking to the bottom. This only takes about 5 minutes and can happen right alongside the boiling pasta.
Take your string cheese sticks and slice them into rounds about ¼ inch thick. Using your cookie cutter or the wide end of a straw, punch a small circle out of the center of the olive slices to nest inside each cheese round later.
Press a piece of sliced black olive into the center of each cheese round to create the pupil. Repeat this until you've made enough eyeballs to top every serving, which usually works out to 4 or 5 per plate.
Divide the warm pasta among bowls and spoon the sauce generously over the top. Scatter your finished eyeballs across each serving so they appear to be staring back up at whoever's eating, then serve right away while everything is still warm.