Quick homemade rye croutons give an unexpected hit of flavor and crunch to the familiar combination of spinach and mushrooms.
Make croutons: Preheat oven to 350. On a rimmed baking sheet, toss bread with 1 tablespoon oil; season with salt and pepper. Bake, tossing occasionally, until bread is golden, 10 to 12 minutes.
Meanwhile, in a medium bowl, whisk together lemon juice and remaining oil; season with salt and pepper. Add spinach, mushrooms, and croutons; toss gently, and top with Parmesan.