1. Heat a PADERNO Classic (1.9 L) Saucepan over medium-high heat. Cook bacon, stirring occasionally until crisp, 3 to 5 minutes. Remove bacon to paper towel-lined plate. Remove fat from pan; wipe out pan and return to stovetop over medium heat.
2. Add half the butter of pan; add leeks and cook, stirring often, until tender, 6 to 8 minutes, lowering heat if they begin to colour. Remove leeks to a bowl; return pan to heat.
3. Add remaining butter to pan; add onion and cook, stirring occasionally, until softened, about 5 minutes. Add celery and garlic; cook, stirring occasionally, until softened, about 3 minutes, lowering heat if vegetables begin to colour.
4. Stir in the flour, cooking for 2 minutes. Slowly pour in the stock; whisk or stir until smooth.
5. Add the potatoes; bring to a boil. Reduce heat, cover and simmer until potatoes are cooked through, about 20 minutes.
6. Remove from heat; stir in the cream. Using an immersion hand blender, carefully blend soup in pot until smooth. Stir in salt, black pepper and celery salt; stir in reserved leeks.
7. Return pot to heat and bring soup back to a boil.
8. To serve, garnish with cheddar cheese, chives and reserved bacon.
Tip: For a vegetarian version, use vegetable stock instead of chicken and leave out the bacon.
