Brown Sugar Cheesecake
Preheat oven to 325°F (170°C). Spray a 9-inch springform pan with baking spray with flour.
For crust: In a large bowl, whisk together oats, ¾ cup (165 grams) brown sugar, flour, and cinnamon; stir in melted butter until well combined and mixture holds together when squeezed. Press into bottom and three fourths of the way up sides of prepared pan.
Bake until crust is fragrant and set, 15 to 20 minutes. Let cool completely. Leave oven on; position oven rack in bottom third of oven.
Wrap a large piece of heavy-duty foil around bottom and up sides of springform pan; place pan in a large oven-safe bag, tucking ends so bag is flush with top edge of pan. (If you do not have an oven bag, wrap pan in a double layer of foil.) Place wrapped springform pan in a large roasting pan.
For filling: In the bowl of a stand mixer fitted with the paddle attachment, beat cream cheese, ¾ cup (165 grams) brown sugar, and salt at medium speed until smooth and creamy, about 3 minutes, stopping to scrape sides of bowl. Add 1 cup (240 grams) sour cream and 1 teaspoon (4 grams) vanilla, beating until combined and stopping to scrape sides of bowl. Reduce mixer speed to low; add eggs, one at a time, beating just until combined after each addition and stopping to scrape sides of bowl. Pour filling into cooled crust. Place roasting pan in oven, and add hot water to roasting pan to come 1 inch up sides of springform pan.
Bake until cheesecake wobbles slightly when pan is gently shaken and an instant read thermometer inserted in center registers 150°F (66°C) to 155°F (68°C), 1½ hours to 1 hour and 45 minutes. Carefully remove roasting pan from oven. Increase oven temperature to 400°F (200°C).
For topping: In a medium bowl, whisk together remaining 1 cup (240 grams) sour cream, remaining 2 tablespoons (28 grams)brown sugar, and remaining 1 teaspoon (4 grams) vanilla; carefully spread onto cheesecake with an off set spatula. Carefully return roasting pan to oven.
Bake until topping is just set, about 5 minutes. Carefully remove roasting pan from oven, and carefully remove springform pan from water bath. Let cheesecake cool completely in pan on a wire rack. (Once pan is cool enough to handle, carefully remove oven bag and foil.) Refrigerate until cheesecake is cold and set, at least 3 hours, or up to overnight, loosely covering with foil only when completely cool to prevent condensation from forming.
Transfer ½ cup (about 124 grams) Butterscotch Sauce to a pastry bag fitted with a small round piping tip (Wilton No. 6), and refrigerate for 30 to 45 minutes.
Run a thin-bladed knife between sides of pan and cheesecake, if needed. Carefully remove sides of pan, and transfer cheesecake to a serving plate. Pipe cold sauce on cheesecake as desired. Serve cheesecake with remaining Butterscotch Sauce. Refrigerate in an airtight container for up to 3 days.
Butterscotch Sauce
In a medium saucepan, bring all ingredients to a boil over medium-high heat, whisking constantly until butter is melted, sugar dissolves, and mixture is well combined. Cook, whisking frequently, until thickened, 8 to 10 minutes. Remove from heat; let cool completely before using. Refrigerate in an airtight container for up to 2 weeks.
