To make the praline: Preheat the oven to 325°F. Spread 1 1/4 cups chopped pecans on a rimmed baking sheet and toast for 10 minutes. Grease another rimmed baking sheet with butter, oil, or cooking spray. In a large saucepan, melt 1 stick of butter over medium heat. Stir in 1 cup brown sugar and 1 tablespoon water. Increase the heat to medium-high and cook at a rapid boil for 7 minutes. Add the baking soda and warm pecans and swirl the pan to incorporate them (do not stir). Take care while you’re swirling the pan, as the mixture will spatter a bit. When the bubbling has subsided, swirl in 1 teaspoon vanilla. Pour the mixture out onto the prepared baking sheet and use a small buttered spatula (preferably offset) to spread the mixture in as thin a layer as possible. Let cool before chopping.
Preheat the oven to 350°F.
To make the crust: In a medium bowl, combine gingersnap crumbs, 3 tablespoons brown sugar, 1/2 cup chopped pecans and 6 tablespoons melted butter, until they form an evenly moist, crumbly mixture. Press the mixture evenly onto the bottom and just slightly up the sides of a 9-inch springform pan. Bake until the crust is fragrant and firm, 9 to 10 minutes. Set aside to cool. Leave the oven on but reduce temperature to 325°F.
To make the filling: In the bowl of an electric mixer fitted with the paddle attachment, or using a handheld mixer, beat the cream cheese at low speed until smooth and creamy, 3 to 5 minutes. Gradually add 1/2 cup brown sugar, 3/4 cup granulated sugar and the salt and continue beating until very smooth and no lumps remain, about 10 minutes. Be sure to scrape down the sides of the bowl occasionally to incorporate all the sugar into the cream cheese.
In a small bowl, whisk together the eggs, 3/4 cup heavy cream and 1 teaspoon vanilla. With the mixer going, gradually stream the egg mixture into the cream cheese mixture, beating well and scraping down the sides of the bowl until smooth and creamy, 2 to 3 minutes longer. Using a rubber spatula, fold in 1 cup of the prepared praline. Pour the filling into the crust and smooth the top.
Bake until the edges of the cheesecake are set but the center still jiggles, 40 to 45 minutes. Let the cheesecake cool completely at room temperature before covering with plastic wrap and refrigerating for at least 8 hours or overnight.
When you’re ready to serve the cheesecake, make the topping: In the bowl of an electric mixer fitted with whisk attachment, or using a handheld mixer, whip 3/4 cup heavy cream, sour cream, and 2 tablespoons granulated sugar at medium-high speed until medium peaks form. Using a rubber spatula, fold in the ½ cup prepared praline. Spread over the surface of the cheesecake. Get yourself a hot, dry knife (heat under hot running water, then wipe dry with a towel) and cut out wedges to serve up.