1. In a blender or food processor, combine the roasted pepper, garlic and 1 tablespoon of the water. Process until smooth; set the coulis aside.
2. Preheat the oven to 450 degrees F. Lightly coat a 9" round cake pan with cooking spray.
3. In a large saucepan, combine the milk, remaining water, olive oil, and salt. Whisk in the cornmeal and place over medium heat. Whisk constantly until the polenta begins to thicken.
4. Reduce the heat to low and resume stirring with a wooden spoon. Cook, stirring frequently, until the polenta pulls away from the sides of the pan (45-50 minutes).
5. Stir in the coulis. Pour the mixture into the prepared cake pan and sprinkle with the cheese.
6. Bake until firm (15-20 minutes). Let stand in the pan for 10 minutes before serving. Cut into wedges and sprinkle with the thyme.