Caramelized Onions:

Melt the butter in a large saucepan.

Add the sliced onions.

Cook over low heat, tossing occasionally with a spatula, about 1 hour or until soft, sweet, and golden brown.

Tart:

Preheat oven to 400° F (205° C). Line a half-sheet rimmed baking tray with parchment.

Unroll puff pastry on a silicone baking mat or lightly floured countertop.

With a sharp paring knife, cut a circle approximately 10 inches in diameter. (I like to trace around a dinner plate.) Save the scraps to make palmiers or puff pastry twists.

Arrange on prepared tray.

With a rubber spatula or small stepped palette knife, spread fig jam evenly over the surface of the pastry, allowing a 1-inch border around the outer edge.

Layer caramelized onions over jam.

Scatter with the goat cheese.

Top with the sliced figs.

Add the lemon slices.

With a pastry brush, brush a thin strip of beaten egg along the pastry border.

Turn up the edges, patting with your fingertips to seal.

Brush pastry with more of the beaten egg.

Bake 25-30 minutes, or until bubbly, flaky, and deeply golden brown.

Drizzle with honey. Sprinkle with chopped rosemary. Season with salt and pepper, to taste.

Slice and serve hot.