Onion-Cheese Tartlets


Pastry:
1 1/2 cups unbleached all-purpose flour
1/2 cup (1 stick) well-chilled unsalted butter, cut into pieces
3 tablespoons (or more) buttermilk
1 egg yolk
1/2 teaspoon salt

Onion Filling:
1 tablespoon vegetable oil
3 small onions, halved and thinly sliced
1 small garlic clove, pressed
4 ounces cream cheese, room temperature
1 tablespoon unbleached all-purpose flour
1 teaspoon dried parsley, crumbled
Salt and freshly ground pepper
2 eggs, room temperature
1/2 cup buttermilk
Dijon mustard
1 tablespoon unsalted butter
Paprika

For pastry: Place flour in medium bowl. Cut in butter until mixture resembles coarse meal. Make well in center; add 3 tablespoons buttermilk, yolk and salt. Mix until dough gathers into ball, adding more buttermilk 1 teaspoon at a time if necessary to bind dough. Gather dough into ball; flatten into disc. Cover and chill at least 20 minutes. (Can be prepared 1 day ahead.)
For filling: Heat oil in heavy large non-stick skillet over medium-low heat. Add onions and garlic and cook until onions are golden brown, stirring frequently, about 25 minutes. Drain. Using electric mixer, beat cheese, flour, parsley, salt and pepper in medium bowl until smooth, stopping occasionally to scrape down sides of bowl. Add eggs one at a time,
blending well. Stir in buttermilk. Preheat oven to 425 degrees F. Roll pastry out on lightly floured surface to thickness of 1/8 inch. Cut out 12 rounds using 3 1/2-inch scalloped cookie cutter. Firmly press rounds into 2-inch non-stick muffin cups. Lightly brush dough with mustard. Spoon 2 teaspoons onions into each dough cup. Pour cheese mixture over, filling almost to top. Dot each with 1/4 teaspoon butter. Sprinkle with paprika. Bake 10 minutes. Reduce oven temperature to 350 degrees F. and bake until filling is set, about 15 more minutes. Cool slightly on racks. Unmold. (Can be prepared 3 months ahead. Freeze airtight. Thaw, then rewarm in 350-degree F. oven until heated through, 12 o 15 minutes.) Serve warm or at room temperature. Makes 12 tartlets.