2-1/2 cups reduced-sodium vegetable, or chicken broth
3/4 cup yellow cornmeal
1/2 teaspoon salt
Spray large saucepan with cooking spray; heat over medium heat until hot. Saute onions, garlic, and basil until tender, about 5 minutes. Add broth and heat to boiling; gradually stir in cornmeal and salt. Cook over low heat, stirring constantly, until thickened, about 10 minutes.
Pour polenta into lightly greased 8-inch cake pan; cool to room temperature. Refrigerate, lightly covered, until polenta is firm, 3 to 4 hours.
Spray large skillet with cooking spray; heat over medium heat until hot. Cut polenta into wedges; cook in skillet over medium heat until browned, 3 to 4 minutes on each side.