Preheat oven to 400 degrees F. Coat a large baking sheet with cooking spray.
Wrap garlic cloves tightly in foil and place on prepared baking sheet. Arrange corn on baking sheet next to garlic and sprinkle corn with the salt. Roast for 15 to 20 minutes, until garlic is soft and corn is golden, turning every 5 minutes to prevent corn from burning. Unwrap garlic and mince. Slice kernels from corn cob.
Combine garlic, corn kernels and chicken broth in a medium saucepan. Set pan over medium-high heat and bring mixture to a boil. Stir in couscous, remove from heat, cover and let stand 5 minutes. Fluff with a fork and stir in green onions and pimento, and toss to combine.