Alsace-Style Onion Tart

For pastry

• ½ lb Puff Pastry (available frozen at most upscale supermarkets)

For filling

• 3 tablespoons unsalted butter
• 2 lb onions, halved lengthwise and very thinly sliced crosswise (10 cups)
• 1 1/4 teaspoons salt
• 1 teaspoon black pepper
• 1 cup crème fraîche or heavy cream
• 4 large eggs
• 1/2 teaspoon freshly grated nutmeg

Note: Additional flavouring may be added such as Thyme, Bacon and Anchovies all work well.

Roll out pastry:

Roll out dough on a floured surface with a floured rolling pin. Cut into 4" squares. Make a "V" cut along two edges of the square about " in from the edge. Pull the outside "V" over to the opposite corner and pinch together (see picture). Chill until firm, about 30 minutes.

Prepare filling:

Add butter to skillet and cook onions with 3/4 teaspoon salt and 1/2 teaspoon pepper over moderate heat, stirring, until just wilted, about 2 minutes. Cover surface of onions with a round of parchment (or cover skillet with a tight-fitting lid) and continue to cook, lifting parchment to stir frequently, until onions are very soft and pale golden, about 20 minutes. Stir in additional flavours if needed, and then remove from heat and cool 10 minutes. Whisk together cream (or creme fraiche), eggs, nutmeg, remaining 1/2 teaspoon salt, and remaining 1/2 teaspoon pepper in a large bowl, then stir in onions.

Fill and bake tart:

Pour filling into tart shell, spreading onions evenly, and bake until filling is set and top is golden, 25 to 35 minutes. Serve warm or at room temperature.

Chef's notes:

• Pictured: One of my favourite topping to Onion Tart is Sauteed Wild BC Mushrooms, cooked in butter with Shallot and Garlic, finished with a splash of vermouth.
• Tart can be baked 1 day ahead and cooled, uncovered, then chilled, covered. Bring to room temperature before serving. Makes 10 first-course servings.