Peel and slice the shallot. Wash, trim and roughly chop the celery. Quarter, core and roughly chop the pear.
If your hazelnuts are not roasted, place them in a dry pan and heat gently until toasted. This will only take a few minutes and you need to be constantly watching them because they burn easily. Once ready, let them cool and chop them roughly.
If using bacon: dice it and place on a baking tray lined with foil or baking paper and cook in a moderate-high oven (180-200°C) until browned and crispy. You can also do this step in a dry pan. Once done, fish it out with a slotted spoon and drain on a plate lined with paper towel.
Heat a pot at medium heat. Add oil and shallot, cook until soft and starting to brown (about 5 minutes), stirring often.
Add celery, cook for another 5 minutes, stirring often.
Add pear, cook for another 5 minutes, stirring often.
Add stock and bring to a boil. Lower heat and cook for another 10 minutes.
Blend soup with a stick blender or using a regular blender or food processor.
Add 3 tbsp of blue cheese and blend once more until smooth.
Serve soup garnished with the rest of the blue cheese crumbled, crispy bacon and hazelnuts.