Preheat the oven to 400 degrees F. Line a large baking sheet with parchment paper or a silpat mat.
In a small bowl, combine the pumpkin puree, brown sugar and pumpkin pie spice.
On a lightly floured surface, roll out the pie dough to 1/4-inch thick. Use a pumpkin cookie cutter to cut out about 20 pumpkin shapes. Use a paring knife to cut-out pumpkin faces in half of the pumpkin shapes.
Place one pumpkin (without any cut-outs) on a floured surface and place a heaping teaspoon of filling in the center. Use a spoon to spread the filling almost to the edges. Lightly dip your finger into water and rub the edge of the pumpkin dough shape with the water. Top with a cut-out pumpkin and lightly press the edges together to seal. Repeat with the remaining shapes and filling.
Place the tarts on your prepared baking sheet. Bake for 18 minutes, or until golden brown.