Preheat your oven to 350°F (175°C). Grease a 9x13-inch baking pan with butter or cooking spray. Prepare your chosen brownie mix or homemade recipe. Pour the batter into the pan and bake for 20 to 25 minutes until a toothpick comes out with moist crumbs. Allow to cool completely.

In a microwave-safe bowl, combine unwrapped caramels and 2 tablespoons of milk. Microwave on high for 1.5 to 2 minutes, stirring halfway. Once melted, stir in chopped pecans. Pour over cooled brownie base.

In a mixing bowl, combine softened butter, creamy peanut butter, powdered sugar, and milk. Blend until smooth and spreadable. Spread frosting over caramel layer evenly.

In a microwave-safe bowl, add chocolate chips and oil. Heat for about 1 minute, stirring until smooth. Drizzle over the peanut butter layer.

Let brownies chill in the refrigerator for at least 30 minutes. Cut into squares and optionally sprinkle with fleur de sel before serving.