Peel and finely dice the onion and garlic. Chop the basil leaves.
Heat the olive oil in a pan and sauté the onion and garlic until translucent and aromatic. Add the tomato paste and cook for 1-2 minutes. Add the diced tomatoes, basil leaves, honey, salt, pepper, and thyme sprigs.
Let the sauce simmer for 20 minutes over medium heat. Remove the thyme, then pour the sauce into a baking dish and preheat the oven to 350°F
Meanwhile, wash the zucchini, trim the ends, and thinly slice lengthwise using a vegetable peeler. Lightly sprinkle with salt and let sit for 10 minutes.
Mix the ricotta with ⅓ cup of the grated Parmesan, sugar, egg, salt, and pepper.
Pat the zucchini slices dry with a paper towel, then arrange five slices side by side, slightly overlapping. Spread 2 tablespoons of the ricotta mixture along the bottom end of each slice and roll them up from there.
Place the zucchini cannelloni seam-down in the baking dish on top of the sauce. Drizzle with some olive oil and sprinkle with the remaining Parmesan. Bake in the oven on the middle rack for 25 minutes.
