Peel the pears, remove the cores, and cut into wedges. Cook with the sugar and a little water until they become soft but still slightly firm. (If using canned pears, this step can be skipped.)
Grill or pan-fry the pancetta slices until crispy, then set aside.
Preheat the oven to 200 °C (390 °F).
Mix half of the blue cheese thoroughly with the sour cream.
Line a baking tray with half of the tortilla chips, then drizzle evenly with the sour cream–blue cheese mixture.
Add the remaining chips, arrange the pear slices and walnuts on top, and crumble the remaining blue cheese over everything.
Bake for about 10 minutes, until the cheese has melted and lightly browned. Keep an eye on it—it can burn quickly.
Sprinkle with the crispy pancetta just before serving.