Melt butter and olive oil in a pot over low to medium-low heat
Add leeks, scallion and garlic with a pinch of salt and pepper. Sweat gently 10–12 minutes until very soft and translucent — no browning
Add white wine and let it cook until evaporated
Add potatoes, stock, bay leaf, and thyme
Bring to a gentle simmer and cover and cook until potatoes are fully tender (about 20 minutes)
Remove bay leaf and thyme and reserve some of the leeks and potatoes
Using an immersion blender blend until smooth
Add cream and mix then add the reserved potatoes and leeks back into the soup
Mix in chopped parsley
Season with salt and pepper to taste
