Preheat your oven to 375°F (190°C).
Make the homemade croutons: Place the cubed bread in a large bowl and drizzle with melted butter or olive oil. Toss to evenly coat the bread cubes. Spread the bread cubes out on a baking sheet in a single layer. Bake for 10-15 minutes, or until the croutons are golden brown and crisp. Allow the croutons to cool completely before adding to the salad.
Prepare the bacon vinaigrette: In a small bowl, whisk together the apple cider vinegar, maple syrup, Dijon mustard, salt, and freshly ground black pepper. Slowly drizzle in the olive oil while continuously whisking, until the dressing emulsifies. Add 2 tablespoons of the reserved bacon grease and whisk again until well combined. Set aside.
Assemble the salad: In a large salad bowl, combine the chopped dandelion greens, quartered hard-boiled eggs, sliced scallions, and leftover protein of your choice. Gently toss the ingredients to mix them evenly.
Dress the salad: Drizzle the bacon vinaigrette over the salad, and toss gently to coat the ingredients evenly. Taste and adjust the seasoning with salt and pepper, if needed.
Add the homemade croutons: Gently mix in the cooled homemade croutons, ensuring they are evenly distributed throughout the salad.
Garnish and serve: Just before serving, sprinkle the crumbled bacon over the top of the salad. Enjoy your Maine Summer Dandelion Salad with Bacon Vinaigrette and Homemade Croutons as a refreshing and hearty side dish, or as a satisfying light meal on a warm summer evening.
Note: For a vegetarian option, substitute bacon with tempeh bacon or simply omit it. Replace bacon grease in the vinaigrette with an additional 2 tablespoons of olive oil.