Preheat oven to 350°F and position the oven rack in the middle. Whisk together pumpkin, eggs, brown sugar, vanilla, and liqueur (if using) in a bowl until combined. Stir together granulated sugar, cornstarch, cinnamon, nutmeg, ginger, and salt in a large bowl. Add cream cheese and beat with an electric mixer at high speed until creamy and smooth, about 3 minutes. Reduce speed to medium, then add the pumpkin mixture and beat until smooth. Pour filling into the crust, smoothing the top, then place the springform pan in a shallow baking pan. Bake until center is just set, 50 to 60 minutes. Transfer to a rack and cool for 5 minutes. (Leave oven on.)