Place poblano peppers on a foil-lined baking sheet; broil 3 inches from heat for 8 minutes or until blackened and charred, turning after 6 minutes. Place in a heavy-duty zip-top plastic bag; seal. Let stand 15 minutes. Peel and discard skins. Cut a lengthwise slit in each chile; discard seeds, leaving stems intact.
Heat a medium saucepan over medium-high heat. Coat with cooking spray. Add zucchini and garlic; cook 4 minutes or until crisp-tender. Stir in 1/2 teaspoon cumin, jalapeño peppers, tomatoes, and tomato sauce; bring to a boil. Reduce heat, and simmer 15 minutes. Remove and discard jalapeño peppers.
Preheat oven to 350°.
Combine remaining 1/2 teaspoon cumin, cheese, chicken, and salt in a medium bowl, tossing to combine. Spoon about 1/2 cup cheese mixture into each chile, and secure with a wooden pick. Place stuffed chiles in an 11 x 7-inch baking dish coated with cooking spray; pour tomato mixture over stuffed chiles. Cover; bake at 350° for 20 minutes. Uncover; bake an additional 10 minutes or until thoroughly heated.