Heat a grill to medium-high, about 425 degrees.
In a medium bowl, whisk together the ricotta, Parmesan, egg, and season with salt and pepper. Set aside.
Place about a 16 x 12 piece of aluminum foil on the countertop or other flat surface. Top with another piece to make a double layer.
In the center of the foil, spread out ¼ cup of sauce and spread it around just enough to cover an area for 2 side-by-side half lasagna noodles (about a 5 x 4 space.) Place the noodle halves vertically down on the sauce (side by side.) Spread the cheese over the lasagna noodles, then top with the zucchini rounds, then more sauce (about 2 tablespoons.) Top with two more lasagna noodle halves and repeat with cheese, zucchini, and sauce. Repeat again with more noodles, cheese, zucchini, and sauce. Top with two more lasagna noodle halves and repeat with remaining cheese, then sauce, and then sprinkle over with mozzarella cheese. Top with two tablespoons of water.
Repeat with remaining ingredients until 6 packets are made. Fold the packets up very carefully, leaving room at the top and sides so that the foil doesn’t touch the top of the lasagna. This is tricky, but the less the foil touches the lasagna, the less it will stick and thus, they’ll be easier to open and serve (you won’t have to peel off the lasagna off the foil.)
Place the packets on the grill for 20 to 25 minutes, shaking the packets after 10 minutes on the grill. Carefully open up the packets slightly after 15 minutes and if the lasagna edges are a little crispy, spoon in some sauce or add a tablespoon or two of water. Refold the packets and continue to grill.
After 20 to 25 minutes, open, cut with a fork and if the lasagna is tender and cooked through, remove the packets from the grill and let rest for 5 minutes, still folded. Carefully open the packets and once steam has escaped, top with pesto, if desired. Serve on plates. If you’d like to serve the grill packets out of the foil, it will take a bit more finessing. The bottom piece of lasagna may have stuck to the foil, but if you peel it off carefully, it has a yummy grilled flavor and is more al dente than the other layers. Enjoy!