Preheat oven to 350°F. Line a 13x9-inch baking pan with heavy duty aluminum foil, extending the foil at least 1-inch above sides of pan. Lightly coat foil with cooking spray.
Crust: In a large bowl use an electric mixer to beat the butter on medium speed for 30-60 seconds. To the bowl add granulated sugar, brown sugar and vanilla. Beat until fully combined around 1-2 minutes. Add the flour; beating just until the a crumbly soft dough forms. Press dough evenly onto the bottom and 1/2-inch up the sides of the prepared pan.
Filling: In a large mixing bowl use an electric mixer to beat the cream cheese on medium-high speed for 2 minutes or until smooth.
Add 1 cup granulated sugar and cornstarch to the bowl. Beat on medium speed until combined. Next, beat in sour cream and the vanilla extract on low just until combined.
To the cream cheese mixture add the salt and eggs. Beat on low just until fully combined. Pour the cream cheese mixture over the crust.
Transfer to the oven and bake for 35-40 minutes or just until the edges are puffed and the center is set when gently shaken. Cool on a wire rack in the pan to room temperature then cover with plastic wrap or foil and chill for at least 2-4 hours, or overnight.
Brulee the Top: Just before serving, lift bars from pan using foil handles. Use a sharp knife to cut into bars wiping the knife with a clean cloth between cuts.
Sprinkle the tops evenly with remaining 1/4 cup sugar. Use a kitchen torch to evenly brown the sugar on the bars.
Chill until serving.
Oven Technique: Alternatively, remove the bars from the pan using the foil handles and carefully transfer to a baking sheet. Position the oven rack to the upper third portion of the oven and broil for 3-5 minutes turning the pan as needed for even browning.