Harvest Corn Chowder with Chorizo

Name: Harvest Corn Chowder with Chorizo
Ingredients: 6 cups fresh corn kernels (cut from 6 to 8 large ears) or frozen kernels, thawed, patted dry (about 2 pounds frozen), divided; 4 cups low-salt chicken broth, divided; 2 tablespoons olive oil; 6 ounces smoked Spanish chorizo,* cut into 1/4-inch cubes (about 1 1/4 cups); 1 1/2 cups chopped onion; 1 pound (about 3 medium) unpeeled red-skinned potatoes, cut into 1/4-inch cubes (about 3 1/2 cups); 2 1/2 teaspoons dried thyme; 1/8 teaspoon (scant) cayenne pepper; 2 cups half and half; Fresh thyme sprigs (for garnish)