In a large sauce pan, sauté the onion in melted butter and oil for at least 2 minutes. Add the squash, sauté for 3 minutes. Add the garlic, sauté for 1 minute. Add the rice, sauté until it is translucent (2 or 3 minutes).
Add the wine and cook until fully evaporated. Add the bouillon, one ladle at a time and stir frequently. Wait until the bouillon is fully evaporated before adding more.
When the rice is al-dente, and the bouillon almost gone, add lemon juice, basil and parmesan.