Preheat oven to 350°. Spray 4 (6-inch) cast-iron skillets with cooking spray.
For blondies: In a medium skillet, melt butter over medium heat. Cook, stirring frequently, until it turns a medium-brown color and has a nutty aroma, about 10 minutes. Remove from heat, and strain through a fine-mesh sieve.
In a large bowl, beat brown butter and brown sugar with a mixer at medium speed until combined, 1 to 2 minutes. Add eggs, one at a time, beating well after each addition. Beat in vanilla.
In a medium bowl, whisk together flour, baking powder, and salt. Gradually add flour mixture to butter mixture, beating just until combined after each addition. Fold in butterscotch morsels and pecans. Divide batter among prepared skillets.
Bake until a wooden pick inserted in center comes out clean, 25 to 27 minutes. Let cool completely.
For topping: In a medium saucepan, bring cane syrup to a boil over medium heat. Boil, stirring frequently, for 1 minute. Remove from heat, and stir in butter until melted. Stir in cream and salt. Let cool completely. Once cool, whisk in confectioners’ sugar; stir in pecans. Pour pecan mixture over cooled blondies. Serve with ice cream, and drizzle with cane syrup, if desired.