In a large pot, heat the olive oil over medium heat. Add the diced onion and sauté for about 5 minutes, or until translucent. Stir in the minced garlic and cook for an additional minute until fragrant.
Add the corn kernels to the pot and sauté for another 5 minutes, stirring occasionally.
Pour in the vegetable broth and bring the mixture to a boil. Reduce the heat and let it simmer for 15 minutes.
Remove the pot from heat and use an immersion blender to puree the soup until smooth. If you don't have an immersion blender, carefully transfer the soup in batches to a countertop blender.
Return the pureed soup to the pot and stir in the heavy cream. Season with salt, black pepper, and cayenne pepper if using. Heat the soup over low heat until warmed through, about 5 minutes.
Serve hot, garnished with fresh basil or chives.