Transfer the dough to a lightly oiled bowl. Cover with plastic wrap and set aside to rise until doubled in bulk - this should take about 2 hours at warm room temperature.

Drizzle a little olive oil over the bottom of a large rimmed sheet pan (13 x 18-inches). Use your hands to gently stretch the dough. Let it rest and relax every few minutes when it starts to resist, until the dough finally reaches the corners of the pan.

Spread the pancetta in one layer in a small ovenproof skillet (such as cast iron). Bake the pancetta 10-12 minutes, until the fat is rendered and the cubes are beginning to crisp. Remove to a paper-towel lined plate.

Slice the potato into very thin slices (about 1/8-inch thick), using a mandoline if you have one or else a very sharp knife. Shingle the slices over the top of the focaccia until they cover the dough.

Sprinkle the onion, red chili and pancetta over the potatoes. Strip the leaves off the thyme stems and scatter over all. Drizzle with a little olive oil.

Bake the focaccia until the edges are golden brown, 20-25 minutes. Remove from the oven and immediately top with the blue cheese. Slice into squares and serve.