Preheat oven to 375°F.  Drain fruit in a colander.  Cut a piece of parchment paper large enough to line a large, rimmed baking sheet.  Lightly flour parchment, unfold pastry onto parchment and roll to a 12x12-inch square. Cut into six 4x6-inch rectangles (2 rows of 3).  Slide parchment on baking sheet and separate pastry creating space between each piece. With a sharp paring knife, cut a shallow rectangle into the pastry 1/2 inch from the edges.  This will rise to form a crust (do not cut all the way through the pastry). Refrigerate until ready to assemble and bake tarts.

Working quickly to keep pastry cold, lightly brush pastry with egg.  For each tart, staying within the cut lines of the rectangle, sprinkle 1 Tbsp. brown sugar and a pinch (about 1/16 tsp.) cinnamon. Place 1/2 Tbsp. butter in the center and top with 1 or 2 pineapple slices or 3 or 4 slices of peach or pear. 

Bake 25 to 30 minutes until pastry is deep golden brown.  Serve warm, as is, or topped with ice cream or whipped cream.