Heat the olive oil over medium heat in your large saucepan. Add the diced onion and cook, stirring occasionally, until the onion is translucent and soft, about 5 minutes. Then add the minced garlic and sauté for another 1 minute until fragrant.
Pour in the vegetable broth and the entire can of diced tomatoes, including the juices. Stir to combine everything well. Bring the mixture to a gentle boil.
Add the orzo pasta to the boiling broth and reduce the heat to a simmer. Cook for about 8 to 10 minutes, stirring occasionally, until the orzo is tender but still holds its shape.
Once the orzo is cooked, lower the heat and stir in the heavy cream and pesto sauce. Mix thoroughly until the soup becomes creamy and the pesto is evenly distributed. Heat through for 2 to 3 minutes but avoid boiling after adding cream to prevent curdling.
Taste the soup and season with salt and pepper as needed. Ladle the soup into bowls and garnish each serving with fresh basil leaves. Serve warm and enjoy.
