Preheat the oven to 350 degrees.
If you need to crush the graham crackers: Place the graham crackers in a large plastic bag. Press all the air out and seal. Crush the crackers with a rolling pin or a wine bottle.
Melt the 2 tablespoons of butter in a small bowl.
Add in the brown sugar and 1/3 cup of the graham cracker crumbs. Mix to combine.
Grease the four ramekins with extra butter.
Evenly distribute the graham cracker mixture into the ramekins and press down to make a firm crust on the bottom of each.
Place on a baking sheet and bake in the oven for 5 minutes. Let the crust cool slightly.
While the crust is cooling, beat the cream cheese (at room temperature) in a large stand mixer (or with a hand mixer) until the cream cheese is light and fluffy—about 3 minutes.
Add in the sugar, brown sugar, and pumpkin pie spice. Beat to combine, about 1 minute.
Beat in the sour cream and pumpkin purée next—about 1 minute.
Add the egg and beat on low until the egg is incporated—about 30 seconds.
Pour the mixture evenly into the four ramekins with the crusts—still on the baking sheet.
Place the baking sheet with the ramekins back in the oven for 20 minutes.
Let the cheesecake cool completely, then refrigerate for 2 hours before serving.