Cut broccoli crowns into florets. Reserve. (If you are using the broccoli stems, remove and discard 2 inches from their ends. Trim the outer fibrous stems with a large knife. Slice thinly.)
Steam the broccoli until just soft enough to blend, about 7 minutes.
Blend the broccoli, garlic and parsley in a food processor until smooth. (It is unnecessary to chop parsley before adding, and the stems can be included).
Stir in the Parmesan.
Spray sheet pans generously with oil and top with tortillas (6 to a pan).
Top each tortilla with heaping 1 oz scoop of pesto, 1/2 cup cheese and 3 slices of plum tomatoes (or 2 of regular tomatoes).
Cover each tortilla with a second tortilla and spray generously.
Bake at 375°F, 6-10 mins (Convection) until lightly brown and crisp. Or bake at 400°F, 8-12 mins (Conventional) until crisp.