How to Make It
In a medium saucepan, cover the potatoes with water and bring to a boil. Add a generous pinch of salt and simmer over moderate heat until tender, about 20 minutes. Drain and pass the potatoes through a ricer into a large bowl; let cool completely.
Meanwhile, preheat the oven to 375°. Spread the bread on a baking sheet and toast in the oven for about 12 minutes, until lightly browned; let cool completely.
In a medium bowl, soak the toasted bread in the milk until softened, about 10 minutes. Squeeze out the excess milk and transfer the bread to a food processor; discard the milk. Add the capers, lemon juice and garlic to the food processor and puree until a paste forms. With the machine on, gradually add the olive oil until incorporated. Add the almonds and pulse until coarsely ground. Add the mixture to the potatoes along with the parsley and mix well. Season the dip with salt and white pepper. Cover and refrigerate for at least 3 hours before serving with toasted baguette slices.