Bake the pie shell in a square or round tart pan according to package instructions. Remove from the oven and let cool slightly.
Meanwhile, combine the cream cheese, Gorgonzola, thyme, salt, and pepper in a medium bowl. Using a hand blender, whip the cheeses together.
In a large, heavy skillet, melt the butter over medium-high heat. Add the pears and cook until golden on both sides, about 5 minutes.
When the tart crust has cooled slightly, gently spread the whipped cheese mixture evenly over the bottom of the tart. Place the pear slices in a decorative pattern over the cheese mixture. Sprinkle the thin strips of prosciutto over the pears.
Cut into squares or wedges and serve.