Preheat oven to 350 degrees F/ 325 degrees F convection.  Oil an 8 inch square pan.

In a large bowl, whisk together the oil, sugars, eggs, vanilla, and espresso.  Allow to sit and rest for about 30 minutes, whisking occasionally.

Stir in the flour and nuts until combined.  Spread half the batter in the pan and then dollop the caramel over the batter.  Dollop the remaining batter and then swirl the caramel and top layer of batter together, trying not to disturb the bottom layer of batter.  Sprinkle with salt and bake 25-35 minutes, until golden brown and crackly on top.  A toothpick should not come out clean because we want gooey blondies!  Cool completely in the pan before slicing and serving with more caramel and hazelnuts.  Blondies may be stored in an airtight container at room temperature for 5 days or frozen, wrapped in parchment and foil and placed in a zipper bag for up to 3 months.  Thaw at room temperature about an hour.