3 tablespoons extra-virgin olive oil
2 medium carrots, peeled and diced into 1/2-inch pieces
1 medium onion, chopped
Kosher salt and freshly ground black pepper
2 tablespoons chopped fresh flat-leaf parsley
2 tablespoons chopped fresh thyme
3 cloves garlic, peeled and smashed or chopped
3 plum tomatoes, diced into 1/2-inch pieces
2 medium zucchini, diced into 1/2-inch pieces
4 cups low-sodium chicken broth
1/3 cup instant polenta, such as Gia Russa
3 tablespoons unsalted butter, at room temperature