Combine water, grits, and salt in a medium, heavy saucepan; bring to a boil, stirring constantly. Reduce heat; simmer, uncovered, 20 to 25 minutes or until grits are very thick, stirring often. (If using polenta, add polenta to boiling water, reduce heat to medium-low, and cook 14 minutes or until very thick.) Remove grits from heat, and stir in Parmesan cheese, garlic powder, and pepper; pour out onto a flat, heat-resistant surface or baking sheet. Spread to about 3/8-inch thickness (10-inch square); allow to cool completely (about 1 hour) so that the mixture is firm to the touch.
Preheat oven to 350°. Once grits are very firm, cut into rounds with a 1 1/2-inch cookie cutter. Place on a baking sheet coated with cooking spray; brush with 1 tablespoon olive oil. Bake at 350° for 15 minutes. Remove from oven; flip rounds over, and brush other sides with remaining 1 tablespoon olive oil. Return to oven, and bake 10 more minutes. Remove and cool completely. Top rounds with salsa, and serve immediately.