Adjust the oven rack to the lower third position and preheat oven to 350°F. Grease or line the bottom and sides of a 9x13-inch baking pan with parchment, leaving an overhang on the longer sides. Set aside.
Make the crust: Combine graham cracker crumbs, melted butter and brown sugar in a bowl and stir so that crumbs and sugar are well saturated with butter. Press mixture into bottom of the prepared baking pan, pressing down with fingers, a spatula or the bottom of a dry measuring cup. Bake crust in preheated oven for 8 minutes. Let cool slightly.
Make the pumpkin layer: In a large bowl, beat all the pumpkin filling ingredients together until smooth. Reserve 1/3 cup of filling. Pour the remainder into warm crust.
Make the cheesecake layer: In a medium bowl using a hand-held or stand mixer filled with a paddle or whisk attachment, beat the cream cheese and Greek yogurt together for 1 minute on medium speed until completely smooth and creamy. Add the sugar, egg and vanilla. Beat on high speed until completely combined. Spread evenly on top of the pumpkin batter.
Drop the remaining pumpkin batter in small spoonfuls on top of the cream cheese. With a spatula or toothpick, begin gently swirling the two together. Jiggle the pan back and forth to get the layers to settle into the pan.
Bake for 40-50 minutes or until the center is no longer jiggly. Remove from the oven, set on a wire rack, and allow to cool completely. Once cool, cover and place in the refrigerator for at least 1 hour and up to 3 days. Remove chilled bars from the pan using the overhang on the sides and cut into squares. Bars are best served chilled.