Heat the oven at 350F.
Start by mixing together 1/3 of a cup of all purpose flour with 1/3 of cup of chestnut flour. Add the yeast and 1/2 of the water. Mix well, kneed and make a ball. Cover it with a clean kitchen towel and let rise in a warm, dry place, until it doubles in size.
Once ready, kneed the dough with the rest of the flour and water, adding also the extra virgin olive oil and the salt. Cover again and let rise for another 2 hours, or until the dough doubles in size once more.
Then, add the walnuts and kneed to incorporate them into the dough. Shape the dough into an oval-shaped long loaf, poking its surface with your fingers, much the way you'd do when preparing focaccia. Let it rest for 20 to 30 minutes.
Bake at 350F for 40 minutes and serve warm.