Place the lettuce in a large bowl. Add dressing, as much as desired, and toss until the leaves are lightly coated. I recommend starting with a little dressing, tossing, and then tasting. You might not need it all.
Add the croutons (however many you want) and Parmesan cheese and toss again. Serve immediately.
Notes
You can use 1 large head Romaine lettuce, discard outer wilted leaves. The dressing and croutons can be made in advance.