Place the oven rack in the middle position. Preheat the oven to 350˚F. Grease a tight-sealing 9" spring-form cake pan with vegetable oil spray.
Combine the carrot cake’s sugar, oil, eggs and vanilla in a bowl. Place flour, baking soda, baking powder, salt, cinnamon and nutmeg in a second bowl and whisk to combine. Mix the dry mixture into the wet. Stir in carrots, walnuts and raisins.
Spoon the batter into the pan and bake 35 to 40 minutes, or until the cake springs back when gently touched in the very centre. Cool cake to room temperature.
Once cooled, wrap and tightly seal the bottom and all the way up the sides of the pan with foil. (Do this well, as this will prevent any chance of water getting into the bottom of the pan when it’s baked with the cheesecake topping).
Preheat the oven to 350˚F again. Place the cream cheese and it’s granulated sugar and vanilla in a bowl and beat with a mixer until well blended. Scrape down the sides of the bowl. Beat in the cheesecake’s eggs, one at a time. Scrape down the sides of bowl again and beat until the mixture is completely smooth.
Spoon and spread the cheesecake batter over the carrot cake in the pan. (The pan will be filled almost to the top; that’s OK.) Set the cake pan in a shallow roasting pan. Pour in enough warm water to come third way up the sides of the cake pan.
Set the roasting pan with the cake in it in the oven and bake 60 minutes, or until the sides of the cake are puffed and the centre of the cheesecake barely jiggles when the pan is tapped.
Set the roasting pan with cake in it on a baking rack and let the cake cool there 30 minutes. Now lift cake out of the roasting pan and cool it to room temperature.
Cover and refrigerate cake 8 hours, or overnight.
To serve, neatly run a sharp knife around the edges of the cake, and then remove the cake pan’s outer ring. Cut the cake into wedges and garnish each wedge with a dollop or piped spiral of whipped cream and few pecan halves.
Serving Suggestions: You can garnish the cake with plain pecan halves, or make things even more decadent by garnishing it with candied pecans. To make them, line a baking sheet with parchment paper. Place 1 cup pecan halves, 1/4 cup granulated sugar, 1 Tbsp. butter, 1/4 tsp. cinnamon and 2 Tbsp. water in a 9” non-stick skillet set over medium heat. Heat and stir the mixture until the pecans are lightly toasted and a syrupy mixture of melted sugar forms around them, about 5 minutes. Spoon the pecans on to the parchment paper, doing so in a single layer. Let pecans cool and they are ready to use.