01 - Preheat oven to 325°F. Generously grease a 9-inch springform pan with butter and line bottom with parchment paper circle.
02 - Combine crushed graham crackers, melted butter, brown sugar, and cinnamon in bowl until mixture resembles wet sand. Press firmly and evenly into pan bottom using back of measuring cup. Bake 10 minutes until lightly golden. Set aside to cool while preparing filling.
03 - Beat softened cream cheese and granulated sugar in large mixing bowl on medium speed until completely smooth and creamy, about 2-3 minutes. Scrape bowl frequently.
04 - Add pumpkin purée, eggs, sour cream, flour, pumpkin pie spice, vanilla, and salt. Mix on low speed just until combined, avoiding overmixing. Scrape sides and bottom to ensure even incorporation.
05 - Pour batter over cooled crust. Tap pan firmly against counter several times to release trapped air bubbles. Smooth top with offset spatula.
06 - Bake 50-60 minutes until edges are set and center jiggles slightly like gelatin. Turn off oven, crack door open slightly, and let cheesecake cool gradually for 1 hour inside oven.
07 - Remove from oven and cool completely at room temperature, about 1 hour. Refrigerate at least 4 hours or overnight, covered loosely with foil, until fully chilled and set.
08 - Whip heavy cream, powdered sugar, and vanilla extract with electric mixer until soft peaks form. Spread or pipe decoratively over chilled cheesecake. Dust with additional cinnamon if desired.
09 - Release springform ring carefully. Slice with sharp knife dipped in hot water, wiping clean between cuts. Serve chilled.