Preheat oven to 375 degrees. Line 2 baking sheets with parchment paper.
Cut each sheet of pastry dough into 4 squares. Place the squares on the baking sheets. Using a fork, prick the dough.
Heat the olive oil in a large saute pan. Add the mushrooms and shallots. Season with salt & pepper. Cook, stirring occasionally, until the mushrooms are softened. About 5 minutes. Add the wine and stir until liquid is evaporated. About 2-3 minutes.
Sprinkle each of the pastry squares with half of the gruyere, leaving a 1/2-inch border. Top each square with mushrooms and remaining cheese. Brush the edges with olive oil.
Bake the tarts until golden brown, about 25 minutes.