Step 1
Preheat oven to 350 degrees F (175 degrees C). Line a 9x13-inch baking pan with parchment paper leaving a 1-inch overhang over each side.
Step 2
Combine brown sugar and butter in a large bowl; beat with an electric mixer until light and fluffy. Beat in eggs and vanilla extract.
Step 3
Whisk flour baking powder and salt together in a separate bowl. Beat flour mixture gradually into the creamed butter mixture until batter is combined. Spread batter in the bottom of the lined baking pan.
Step 4
Mix white sugar and cinnamon together in a small bowl. Sprinkle 2 tablespoons of the cinnamon sugar over the batter.
Step 5
Bake in the preheated oven until edges are light brown 25 to 30 minutes. Transfer to a wire rack to cool completely about 15 minutes.
Step 6
Spread dulce de leche over cooled crust.
Step 7
Combine white chocolate heavy cream and light corn syrup in a small saucepan. Cook and stir over low heat until smooth about 5 minutes. Let cool slightly about 5 minutes.
Step 8
Spread white chocolate mixture over dulce de leche. Sprinkle remaining cinnamon sugar on top. Cover baking pan and refrigerate until firm at least 1 hour.
Step 9
Lift out of the baking pan using the parchment paper ends. Cut into bars.