Pumpkin White Chocolate Mousse Cheesecake

From Mel

We had this for Thanksgiving '15 and Jonathan loved it, describing the topping as "truly comforting". As always, I cut the sugar significantly in all three layers and it was delicious. Per Mel's instructions, I just added all parts of the topping except the chocolate to the blender and blended until smooth, then I added the chocolate and pulsed a few times.

• 2 cups graham cracker crumbs (about 14 rectangle crackers)
• 2 tablespoons brown sugar (or...none)
• 1/2 teaspoon ground cinnamon
• 1/8 teaspoon ground nutmeg
• 8 tablespoons butter, melted
Cheesecake:
• 3 (8 ounces each) packages cream cheese, softened
• 1 1/2 cups sour cream
• 3 tablespoons cornstarch
• 1 1/2 cups granulated sugar (or...2/3 cups)
• 1 teaspoon ground cinnamon
• 1/2 teaspoon ground nutmeg
• Pinch of cloves
• 1 teaspoon vanilla extract
• 1 (15-ounce) can pumpkin puree (or about 2 cups if using homemade)
White Chocolate Topping:
• 1 cup heavy whipping cream
• 1/4 teaspoon vanilla extract
• 2 tablespoons powdered sugar (or...1)
• 1/4 teaspoon ground cinnamon
• Pinch ground nutmeg
• 4 ounces cream cheese, softened
• 4 ounces white chocolate, melted

DIRECTIONS

1. For the crust, preheat the oven to 375 degrees F. Combine the graham cracker crumbs, sugar, cinnamon, and nutmeg. Stir in the melted butter and mix until combined and it looks like wet sand. Press the crumbs into the bottom and just a bit up the sides of a 10-inch springform pan. Place the springform pan on a foil-lined larger baking pan and bake for about 8 minutes until the crust is just lightly golden and smells fragrant. Remove from the oven and let cool. Reduce the heat to 350 degrees F. 
2. For the cheesecake batter, in the bowl of an electric stand mixer fitted with the whisk attachment (or in a bowl with a handheld electric mixer), whip together the cream cheese and sour cream until just combined. Add the cornstarch, sugar, cinnamon, nutmeg and cloves and mix until incorporated. Mix in the vanilla and pumpkin until just combined. 
3. Spread the batter evenly over the crust and bake (keeping the pan still on the foil-lined baking sheet; helps prevent any leaking butter/batter from dirtying your oven) for 45-60 minutes, until the edges are set and the center slightly jiggles. Let the cheesecake cool completely. 
4. For the white chocolate topping blend all ingredients (except chocolate) in blender until smooth. Then fold in chocolate. [Mel has instructions for using a hand mixer instead]. In a separate bowl, beat the cream cheese until fluffy. Add the white chocolate and mix until smooth and creamy. Fold in the whipped cream, taking care not to deflate the whipped cream, and mix gently with a rubber spatula, lifting and turning the cream, until the mousse is combined and creamy.
5. Spread the white chocolate topping on top of the cooled cheesecake. Refrigerate for at least 1-2 hours or up to a day. Garnish with a light dusting of freshly grated nutmeg, if desired.