Flemish Caramelized Onion Tart

Prepare tart shell: In food processor fitted with metal blade, combine flour and salt. Pulse once or twice to blend and aerate.  Add butter and bacon fat; pulse until a coarse mixture forms. Gradually pulse in ice water until dough begins to stick together.

Remove blade and gather dough pieces into a ball; do not handle too much. Wrap with plastic wrap, shape into a large disk and refrigerate 30 minutes.

Preheat oven to 350 F. Remove the chilled dough; allow it to warm at room temperature for 5 to 7 minutes.

On lightly floured surface, roll out dough to 14-inch diameter. Fold dough in half; place evenly on one side of greased and floured 10-inch tart pan. Gently unfold dough and carefully shape it evenly into pan. Run a rolling pin along edge around perimeter of pan to trim off excess dough. Line pie shell with fill and fill with dried beans or pie weights.

Bake pie shell at 350 F. for 7 to 9 minutes or until parbaked. Cool on wire rack; remove weights and foil before assembly.

Meanwhile, prepare filling: In 10-inch skillet over medium-high heat, melt butter until hot but not smoking. Add onions; saute 5 to 7 minutes or until they begin to brown. Reduce heat; continue cooking onions, stirring occasionally, for 15 to 20 minutes or until well-caramelized. Season onions to taste with salt, pepper and nutmeg; add thyme leaves and set aside to cool.

In medium bowl, beat eggs and cream; stir in ¾ cup shredded gruyere and cooled onions. Pour mixture into parbaked crust; top with remaining ¼ cup cheese. Bake 35 to 40 minutes or until firm and golden.