Step 1

Preheat oven to 425°. Tear ½ boule sourdough bread into 1" bite-sized pieces, using only the fluffy white interior and discarding the crusts (you should have about 3 cups).

Step 2

Place bread in a large bowl and drizzle with 3 Tbsp. oil. Season with salt and pepper and toss to coat.

Step 3

Transfer bread to a small rimmed baking sheet and arrange in a single layer (reserve bowl for making the salad). Bake, shaking sheet to toss once halfway through, until croutons are golden and crispy all over but still squishable in the center, 10–12 minutes. Let cool. (You’re done with the oven, so shut it off.)

Step 4

While croutons bake and cool, assemble your dressing. Finely grate 1 garlic clove into reserved bowl with a microplane.

Step 5

Place 1 anchovy (if you’re a fan of anchovies and want to taste them in the dressing, use on a cutting board and mash into a paste with the flat side of a chef's knife. Add to bowl with garlic.

Step 6

Whisk 2 Tbsp. mustard, 2 Tbsp. lemon juice, and 2 Tbsp. mayonnaise into bottom of bowl until mixture is incorporated.

Step 7

Whisking constantly, slowly stream in remaining ⅓ cup oil. Continue whisking vigorously until you have a thick, creamy, smooth dressing.

Step 8

Using a vegetable peeler, shave 3 oz. Parmesan into shards, then break up any larger pieces with your fingertips.

Step 9

Tear 2 romaine hearts into bite-sized pieces directly into bowl with dressing. Season lightly with salt, then generously with pepper.

Step 10

Add about three-quarters of cheese and about three-quarters of croutons to salad and toss gently with clean hands until lettuce is coated. If romaine hearts were small and salad looks a little overdressed, add some of the remaining romaine heart.

Step 11

Transfer salad to a platter. Top with remaining cheese and croutons.