In a large bowl, beat 3 packages of softened cream cheese and brown sugar on medium speed until light and fluffy (and no lumps), scraping down the sides of the bowl.
In a separate bowl, stir together pumpkin pie mix, eggs, sour cream, flour, pumpkin pie spice, and vanilla extract. Mix until well combined.
Add pumpkin mixture to the cream cheese mixture and continue mixing on low speed until well combined, scraping down the sides of the bowl.
Transfer filling into pre-baked crust and bake on the middle rack at 350 degrees for 1 hour.
After 1 hour, turn off oven, prop oven door slightly and let cheesecake stay in oven for additional 45 minutes.
Remove from oven and let cool to room temp before covering with plastic wrap and refrigerating.
Serve when fully chilled (at least 4 hours in the refrigerator or overnight).
Before serving, carefully remove cheesecake from springform pan by running a blunt knife along the sides of cheesecake to release from the springform mold.
Add whatever toppings you desire (whipped cream, caramel sauce, chocolate sauce, etc).
Enjoy!