Preheat the oven to 350°F and line a small 8x8 baking pan with parchment paper.
In a mixing bowl, stir together the melted butter and brown sugar until smooth. Add the egg and vanilla extract, then mix until combined.
Whisk in the flour, baking powder, and salt until no dry streaks remain. Fold in the white chocolate chips.
In a small saucepan over low heat, combine the candy corn and heavy cream. Stir until the candy corn melts into a smooth, thick mixture.
Pour the blondie batter into the prepared pan and spread evenly. Drop spoonfuls of the melted candy corn mixture over the top, then use a knife to gently swirl it through the batter.
Bake for 20 to 22 minutes until the edges turn golden and a toothpick comes out with a few moist crumbs. Cool completely in the pan before cutting into bars.