Heat oven to 350ºF Butter a 10.5"x7" baking dish.

In a small saucepan set over medium heat, melt the butter. Add the brown sugar and stir until dissolved. Remove from heat and let cool slightly. Beat in the egg and vanilla. Stir in the salt, flours, and chocolate chips.

Pour the batter into the prepared pan. Spoon the apple butter into four strips, across the short edge of the pan. Drag your spoon through the batter the long way to drag the apple butter along and create the pretty marbled effect.

Bake 40-45 minutes or until set in the middle.

Let cool completely, then cut into 15 blondies.