Position the baking sheet on the upper oven rack and bake for 8 minutes. Afterward, switch to broil for an additional 2 to 5 minutes, or until the edges of the bread turn a crisp, golden brown. Once out of the oven, sprinkle the bread with grated Parmesan, flaky sea salt, fresh parsley, and red pepper flakes, if using. Cut into slices and serve while still hot.