Stir together crumbs, hazelnuts, sugars and olive oil in a bowl until combined well. Press crumb mixture evenly into the bottoms of 4 mini tart pans.
Chill the crusts for about 1 hour.
Put the oven rack in the middle position and preheat the oven to 350°F.
Whisk together pumpkin, eggs, brown sugar,cream, vanilla, and bourbon (if using) in a bowl until combined.
In a separate bowl, 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 the tops. Bake until center is just set, 50 to 60 minutes. Transfer to rack and cool 5 minutes. Sprinkle with cocoa toasted hazelnuts.