Preheat the oven. Preheat oven to 375°F. Lightly grease a standard 12-cup muffin tin.
Prepare the crusts. Roll out the pie dough and cut twelve 4-inch circles, rerolling scraps as needed. Gently press each circle into a muffin cup, forming a small pie shell.
Mix the filling. In a medium bowl, whisk together pumpkin puree, maple syrup, eggs, milk, pumpkin pie spice, vanilla, and salt until smooth.
Fill the crusts. Divide the pumpkin filling evenly between the prepared pie shells, filling each about three-quarters full.
Bake. Bake for 25–30 minutes, until the crusts are lightly golden and the filling is nearly set with a slight jiggle in the center.
Cool. Allow the pies to cool in the muffin tin for approximately 20 minutes. Carefully remove and transfer to a wire rack. Refrigerate for at least 1 hour or until chilled.
Make the decorations. Roll out the remaining pie dough. Use small fall-shaped cookie cutters to create leaves, pumpkins, or acorns. Arrange on a parchment-lined baking sheet, brush with milk or egg wash, and sprinkle with cinnamon sugar if desired. Bake at 375°F for 8–12 minutes until golden. Cool completely.
Prepare the maple whipped cream. Using a hand mixer or stand mixer, whip the heavy cream, maple syrup, and vanilla until medium-stiff peaks form.
Decorate. Pipe or spoon maple whipped cream onto each chilled mini pumpkin pie. Top with a baked fall-shaped pie crust decoration.
Serve. Enjoy immediately, or refrigerate until ready to serve.