Start by heating the olive oil in a large skillet or deep pan over medium heat. Add the diced onion and cook until it becomes translucent and fragrant, about 3-4 minutes. Toss in the minced garlic and cook for another minute, stirring constantly to avoid burning. Now, add the diced zucchini and sauté until just softened but still slightly firm, about 5 minutes.
Add the orzo pasta directly to the pan with the vegetables. Stir constantly for 2-3 minutes, allowing the orzo to toast lightly.
Pour in the vegetable broth, dried oregano, salt, and black pepper. Stir everything to combine well. Bring the mixture to a gentle boil, then reduce the heat to low. Let it simmer uncovered, stirring occasionally, until the orzo is tender and has absorbed most of the broth, about 10-12 minutes.
Once the orzo is cooked and the broth is mostly absorbed, stir in the heavy cream and grated Parmesan cheese. Continue cooking over low heat, stirring frequently, until the risotto turns creamy and luscious, about 3-5 minutes.
Remove the pan from heat and gently fold in the chopped fresh basil leaves. Taste to adjust seasoning if necessary, adding more salt or pepper as desired. Serve immediately for the best texture and flavor.