Step 1Heat the oven to 400 degrees.
Step 2Place the parsley, lemon zest, garlic, butter and salt in a mini-processor or small bowl. Mix until smooth.
Step 3Spread each quarter of the bread with the mixture, dividing evenly. (This can be made a day ahead and refrigerated or frozen up to 1 month.)
Step 4To serve, bake the bread, cut side up, in a single layer on a baking sheet until just beginning to brown, about 15 minutes (bake the bread slightly longer if frozen). Cut each into 4 pieces. Serve hot.