01 - Preheat oven to 350°F (175°C). Grease a 13x18-inch rimmed baking sheet and, if preferred, line with parchment paper.
02 - In a large mixing bowl, whisk together the melted butter and granulated sugar until fully incorporated. Add eggs and vanilla extract and beat until mixture is smooth.
03 - In a separate bowl, blend all-purpose flour, baking powder, baking soda, and salt thoroughly.
04 - Gradually add half of the dry mixture to the wet ingredients, followed by half of the milk, gently stirring until just combined. Repeat with remaining dry mixture and milk until batter is uniform.
05 - Carefully fold the chopped pecans into the batter, ensuring even distribution.
06 - Transfer batter onto the prepared baking sheet, smoothing surface with an offset or silicone spatula.
07 - Bake for 20 to 25 minutes, or until a toothpick inserted in the center comes out clean.
08 - While the cake bakes, melt butter and brown sugar in a saucepan over medium heat, stirring until sugar dissolves, about 2 to 3 minutes. Stir in milk and bring to a gentle boil for 1 minute. Remove from heat, whisk in vanilla extract, then gradually add powdered sugar, whisking until smooth.
09 - Pour warm caramel glaze evenly over hot cake. Sprinkle with 1/2 cup additional chopped pecans.
10 - Allow cake to cool completely before cutting into squares for serving.