In a medium-sized pot, combine the sugar, salt, cream of tartar, and water. Cook over medium-high heat, swirling (not stirring) the pan often so the sugar melts evenly. Once it comes to a boil, reduce the heat to medium. When the color turns a medium amber, remove from heat and add butter one cube at a time, swirling with each addition. Then, pour in the heavy cream and vanilla and stir until completely smooth. 

Allow the caramel to cool for a few minutes before transferring to a glass jar. Place in the fridge until ready to use. 

Preheat the oven to 350 degrees F. Grease a 9x9 inch square pan and line with parchment paper. 

Start by making the brown butter. Heat the butter over medium heat in a sauce pan for several minutes, swirling to even out the color. The butter will be ready once the fat solids have separated and darkened, and the butter is an even medium amber color. Transfer to a bowl and allow to cool as you prepare the other ingredients.  

In a medium bowl, whisk together the flours, baking powder, and salt. Set aside.

In a separate bowl, mix together the brown sugar and brown butter until fully combined. Then, mix in the eggs and vanilla. 

Fold the dry ingredients into the wet until just combined. Then, fold in the chocolate chunks. 

Press the dough into the prepared pan, smoothing it out to make as even as possible.

Drizzle a small amount of caramel on top of the blondie dough and use a tooth pick to swirl it. 

Bake the blondies for 30-35 minutes. Allow to cool completely before cutting.