Preheat your oven to 350°F (175°C).

Wrap the bottom of a springform pan with aluminum foil.

In a mixing bowl, combine cold unsalted butter, brown sugar, all-purpose flour, pumpkin pie spice, and a pinch of salt. Blend until crumbly and chill for 30 minutes.

Crush Biscoff cookies in a food processor, then mix with melted butter and sugar. Press into the bottom of the pan and bake for 15 minutes.

In a bowl, beat cream cheese, sugar, and cornstarch until smooth. Gradually add pumpkin purée, sour cream, vanilla, and pumpkin pie spice until silky.

Add eggs one at a time, mixing on low speed to maintain a light texture.

Pour half of the cheesecake batter over the crust, sprinkle with streusel, then pour remaining batter on top.

Place the pan in a roasting pan and fill with boiling water. Bake for 1.5 hours, then turn off the oven and leave it in for another hour.

Cool on the counter for 30 minutes, then refrigerate overnight.

Whip heavy cream with powdered sugar until stiff peaks form and use to top the cheesecake before serving.