Chop basil in processor. Add butter, capers, salt and generous amount of pepper and process until well combined. (Can be prepared 2 days ahead. Cover and refrigerate. Bring butter mixture to room temperature before using.)
Preheat oven to 500°F. Arrange bread cut side up on cookie sheets. Bake until golden brown, about 5 minutes. Spread cut surfaces with basil butter. Cut crosswise and serve.
