- Preheat oven to 500°F.
- When the focaccia is fully risen and ready to bake, gently spread onion marmalade evenly over surface. Evenly distribute blue cheese over onion marmalade and scatter walnuts over the top.
- Place the sheet pan on the middle shelf of the oven, lower temperature to 450°F, and bake for 20 minutes. Rotate pan 180 degrees and bake for 20 to 25 minutes, until the dough is golden on the bottom and top.
- When the baking is complete, set up a cooling rack inside a sheet pan and immediately remove the focaccia from the pan by using a metal spatula or pastry blade to break all contact with the walls of the pan. Place the spatula or blade between the focaccia and the parchment or pad and lift the edge up. Then jiggle the focaccia out of the pan onto the cooling rack. Pour any excess oil from the pan over the top of the focaccia. Let the focaccia cool for at least 20 minutes before slicing and serving.