Preheat oven to 350℉ and line a 12-count muffin tin with paper liners.
In a small bowl, stir together the graham cracker crumbs and brown sugar. Add the melted butter and stir until well-combined.
Divide the crust mixture evenly between the 12 wells of the muffin tin (about 2 tbsp each). Press the crust mixture down firmy with a spoon or shot glass. Bake in the preheated oven for 7-8 minutes, or until turning golden brown. Set aside to cool for at least 10 minutes.
Meanwhile, make the pumpkin cheesecake filling. Add the cream cheese and granulated sugar to the bowl of a stand mixer and, using the whisk attachment, whisk for 1-2 minutes until smooth and creamy.
Add the pumpkin puree, egg and egg yolk, pumpkin pie spice, and vanilla and whisk again until well combined.
Divide the pumpkin mixture evenly between the 12 cooled graham cracker crusts (about 3 tbsp in each well). Bake the mini pumpkin cheesecakes in the preheated oven for 20 minutes.
After baking, remove from oven and allow to cool for 30 minutes at room temperature. Cover the pan with plastic wrap and place in the fridge for at least 2 hours before removing the paper liners and serving.
Top each with whipped cream and/or a dust of pumpkin pie spice, then serve!