Preheat the oven to 350°F.
Line a 9x5x3-inch bread loaf pan with non-stick foil.
In a medium bowl, stir together the melted butter, sugar, egg yolk and whiskey. Stir very well until homogenous.
Next, sprinkle the flour, baking powder, pecans and chocolate chunks on top. Stir for 50 brisk strokes (this helps make the blondies chewy and the tops shiny).
Pour the batter into the prepared pan, and bake on top of a baking sheet for 19-22 minutes, or until the edges of the bars start to turn golden and the surface starts to become shiny and crack.
Remove from the pan, and let cool before slicing and serving.