Preheat your oven to 350°F (175°C).
Grease your 9x13-inch baking pan or line it with parchment paper.
In a large mixing bowl, whisk together the melted butter and light brown sugar until smooth. Add peanut butter, eggs, and vanilla extract, mixing until well combined.
In a separate bowl, whisk together the flour, baking powder, baking soda, and salt. Gradually add to the wet ingredients, stirring until just combined.
Gently fold in the Rolo candies.
Pour the batter into the prepared pan, spreading it evenly. Bake for 25-30 minutes, or until edges are golden brown.
Allow to cool in the pan for 10 minutes, then transfer to a wire rack to cool completely before cutting.