Onion, Mushroom And Sage Custard Tart Recipe

Ingredients

• 5 tablespoons cold butter
• 3/4 cup all-purpose flour
• Scant 1/2 cup whole wheat flour
• 5 tablespoons small-curd cottage cheese
• 1/2 teaspoon salt
• 1/2 tablespoon cold water
• 3 large yellow onions
• 2 tablespoons butter
• 1 1/2 tablespoons granulated sugar
• 1/4 cup good-quality balsamic vinegar
• Salt and pepper
• 2 ounces mixed wild mushrooms
• 15 to 20 sage leaves
• 3 large eggs
• 1/3 cup whole milk
• 1/3 cup heavy cream
• 1/4 cup finely grated Parmesan