- 1 medium onion, finely chopped
- 2 flat anchovy fillets, rinsed and chopped
- 1/2 cup chopped red bell pepper
- 1/2 cup chopped yellow bell pepper
- 1/2 teaspoon finely chopped fresh rosemary
- 3 tablespoons extra-virgin olive oil
- 1/2 cup Niçoise or other brine-cured black olives, pitted and coarsely chopped
- 1 1/3 cups all-purpose flour
- 2 teaspoons baking powder
- 1/2 teaspoon salt
- 3 1/2 tablespoons cold unsalted butter, cut into small pieces
- 1/2 cup whole milk
- Cook onion, anchovy, bell peppers, rosemary, a rounded 1/4 teaspoon salt, and 1/8 teaspoon pepper in oil in a heavy medium skillet over medium heat, stirring occasionally, until onion is golden, about 10 minutes. Transfer to a bowl and stir in olives, then cool filling.
- Preheat oven to 400°F with rack in middle.
- Whisk together flour, baking powder, and salt in a bowl. Blend in butter with a pastry blender or your fingertips until most of mixture resembles coarse meal with some small (roughly pea-size) butter lumps. Add milk and stir with a fork until a shaggy dough forms. Gently knead dough 8 to 10 times with floured hands on a lightly floured surface.
- Roll out dough into a 12-inch square (1/4 inch thick) on a lightly floured surface with a floured rolling pin. Cut into 3 equal strips. Arrange strips 1 inch apart on an ungreased baking sheet and spread with filling, leaving a 1/2-inch border around edges.
- Bake until crust is golden, 20 to 25 minutes. Transfer to a rack using a large metal spatula and cool to warm or room temperature. Cut crosswise into 1-inch pieces.