How to Make It
Heat oven to 400° F. On a rimmed baking sheet, toss the bacon and bread; season with ¼ teaspoon salt and ⅛ teaspoon pepper. Roast until the bacon is crisp, 10 to 12 minutes; let cool.
In a large bowl, whisk together the buttermilk, mayonnaise, herbs, 1/4 teaspoon salt, and ⅛ teaspoon pepper. Add the spinach, cucumber, and crouton mixture and toss to coat.