Spicy Turnip Soup

Name: Spicy Turnip Soup
Ingredients: 2 bunches turnips, including greens (about 1 1/2 - 1 3/4 lbs total); 1 1/2 tablespoons olive oil, divided; 2-3 sprigs plus 1/2 tsp chopped fresh thyme, divided; 1 teaspoon salt, divided; 1 leek, white and light green parts only, sliced thin; 3 garlic cloves, smashed; 1/8 teaspoon plus a pinch Chinese Five Spice Powder, divided; 1/2 tablespoon unsalted butter; 1 pound Yukon Gold potatoes, sliced; 3 cups vegetable stock; 1 1/2 cups half-and-half or milk; 1 teaspoon cider vinegar