1
Preheat the oven to 350°F. Spread out the bread cubes on a baking sheet and roast until crisp, about 10 minutes.
2
To make the bechamel, melt the butter in a skillet over medium heat. Whisk in the flour and cook on low heat for 10 minutes.
3
In a separate saucepan over low heat, warm the milk. Turn off the heat and whisk the milk into the roux. Return the heat to medium and bring to a simmer, whisking constantly. Continue to simmer (not boil) for 15 minutes, whisking occasionally. Season with salt.
4
Heat a large stock pot over medium heat. Add the bacon and cook, flipping once, until crisp. Transfer the bacon to a paper towel-lined plate, let cool, then roughly chop.
5
Pour out most of the bacon fat, and melt the butter in the pot. Add the onion and celery and cook, stirring, until softened but not colored, 5-7 minutes.
6
Add in the cooked bacon and wine and bring to a simmer. Stir in the clams, clam juice, cream, bechamel, and stock. Simmer for 10 minutes, then stir in the potatoes and cook for another 10 minutes, until fork-tender. Taste and adjust seasoning with salt and pepper.
7
To serve, divide the soup between bowls. Garnish with croutons and parsley.