Roasted Carrot Soup

Name: Roasted Carrot Soup
Cuisine: American
Ingredients: 1 3/4 pound carrots (6 to 8 large carrots); 1/4 cup olive oil, divided; 1 pinch (or more) kosher salt; 5 cup (or more) low-sodium, high-quality vegetable stock; 1 (1-inch) piece ginger, peeled; 1 sprig thyme, plus more for garnish; 1/2 large sweet onion, chopped; 2 large garlic cloves, chopped; 1 pinch freshly ground black pepper