Once onions for this nibble-and-mingle pizzalike tart have been caramelized by cooking in butter, their taste goes from sharp to sweet. Moisture content varies with onions, so when cooking them, lower the heat or add a small amount of water as needed to keep them from burning.

Caramelized-Onion Tart

In a large skillet, melt butter over medium-high heat. Add onions. Sprinkle with salt. When onions begin to sweat, reduce heat to medium-low. Cook, covered, for about 40 minutes or until onions are very soft and caramel in color, stirring occasionally.

Meanwhile, preheat oven to 400 degrees. Line a baking sheet with parchment paper; set aside.

From one puff pastry sheet, cut sheet into 1/2-inch wide strips; set aside.

On a lightly floured surface, roll second puff pastry sheet to a 10-by-12-inch rectangle. Cut rectangle in half for two 5-by-12-inch sections. Place on prepared baking sheets. Lightly brush with water a 1/2-inch band around each edge. Place the 1/2-inch wide strips around the pastry edges, trimming as needed without overlapping.

Inside the strips, sprinkle pastries with cheese. Top with caramelized onions and olives. Brush top edges with beaten egg. 

Bake for 15 to 20 minutes or until lightly golden. Cool slightly on a wire rack. If desired, garnish with dill.