Gourmet Pumpkin Cheesecake

For crust
3/4 cup graham cracker crumbs (from five 4 3/4- by 2 1/4-inch crackers)
1/2 cup pecans (1 3/4 ounce), finely chopped
1/4 cup packed light brown sugar
1/4 cup granulated sugar
1/2 stick (1/4 cup) unsalted butter, melted and cooled

For filling
1 1/2 cups canned solid-pack pumpkin puree (not pie filling)
3 large eggs
1/2 cup packed light brown sugar
2 tablespoons heavy cream
1 teaspoon vanilla
1 tablespoon bourbon liqueur or bourbon (optional, I usually up it to 2 TBSP)
1/2 cup granulated sugar
1 tablespoon cornstarch
1 1/2 teaspoons cinnamon
1/2 teaspoon freshly grated nutmeg
1/2 teaspoon ground ginger
1/2 teaspoon salt
3 (8 ounce) packages cream cheese, at room temperature

For topping
2 cups sour cream (20 ounces)
2 tablespoons granulated sugar
1 tablespoon bourbon liqueur or bourbon (optional)

Garnish: pecan halves

Make crust: Invert bottom of a 9-inch springform pan (to create flat bottom, which will make it easier to remove cake from pan), then lock on side and butter pan.

Stir together crumbs, pecans, sugars, and butter in a bowl until combined well. Press crumb mixture evenly onto bottom and 1/2 inch up side of pan, then chill crust, 1 hour.

Make filling and bake cheesecake: Put oven rack in middle position and Preheat oven to 350°F.

Whisk together pumpkin, eggs, brown sugar, cream, vanilla, and liqueur (if using) in a bowl until combined.

Stir together granulated sugar, cornstarch, cinnamon, nutmeg, ginger, and salt in 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 pumpkin mixture and beat until smooth.

Pour filling into crust, smoothing top, then put springform pan in a shallow baking pan (in case springform leaks). Bake until center is just set, 50 to 60 minutes. Transfer to rack and cool 5 minutes. (Leave oven on.)

Make topping: Whisk together sour cream, sugar, and liqueur (if using) in a bowl, then spread on top of cheesecake and bake 5 additional minutes.

Cool cheesecake completely in pan on rack, about 3 hours.

Chill, covered, until cold, at least 4 hours. Remove side of pan and bring to room temperature before serving.

Do ahead: Baked cheesecake can be chilled, covered, up to 2 days.