Three-Onion Tart with Taleggio

Preparation

1. Make crust:

   Step 1

   Mix flour and salt in large bowl. Make well in center of flour mixture. Add egg and oil to well. Pour melted butter and milk into well. Mix ingredients in well, gradually incorporating flour until dough forms. Turn dough out onto floured surface and knead until smooth, about 10 minutes. Form into ball. Wrap in kitchen towel; let stand at room temperature 2 hours.

2. Make topping:

   Step 2

   Combine leeks and oil in large nonstick skillet. Cover and cook over medium-low heat until leeks are tender but not brown, stirring frequently, about 15 minutes. Stir in red onion and green onions. Sauté uncovered until all onions are very tender, about 25 minutes longer. Season with salt and pepper. Cool. Mix in egg, then Taleggio cheese.

   Step 3

   Preheat oven to 375°F. Roll out dough on floured surface, forming 13-inch round. Transfer to large rimless baking sheet. Fold outer 1 inch of dough over, forming double-thick rim. Spread topping evenly over crust. Bake tart 10 minutes. Sprinkle Parmesan over. Bake until crust is golden, about 15 minutes longer. Cut into wedges.