Preheat oven to 375°F (190°C). In a large bowl, toss the bread cubes with olive oil, everything bagel seasoning, garlic powder, and fine sea salt until evenly coated.

Spread the coated bread cubes in a single layer on a baking sheet lined with parchment paper. Bake for 10–14 minutes, stirring halfway through, until golden brown and crisp. Remove from oven and let cool completely on the sheet; croutons will continue to crisp as they cool.

Harvest Caesar Dressing

Whisk dressing

In a medium bowl, combine mayonnaise, Greek yogurt, lemon juice, Dijon, Worcestershire, apple cider vinegar, minced garlic, maple syrup, and grated Parmesan. Whisk until smooth.

Slowly drizzle in the extra-virgin olive oil while whisking to emulsify. Taste and season with salt and freshly ground black pepper. If you prefer a thinner dressing, whisk in up to 2 tablespoons of water or additional buttermilk one teaspoon at a time until desired consistency is reached. Chill in refrigerator for at least 15 minutes to let flavors meld.

Salad Assembly

Prepare lettuce and onion

Trim any coarse outer leaves from the Little Gem heads and halve each head lengthwise through the core. Rinse and spin or pat dry thoroughly. Thinly slice the red onion crosswise into half-moons; if raw onion is strong, soak slices in cold water for 5 minutes, then drain and pat dry.

Arrange halved Little Gem heads cut-side up on a serving platter or individual plates (2 halves per person). Tuck a few red onion slices between and over the lettuce halves for bite and color.

Drizzle about 1 to 1.5 tablespoons of Harvest Caesar dressing over each Little Gem half (adjust to taste). Sprinkle a generous pinch of freshly ground black pepper and a light dusting of coarse kosher salt over the assembled lettuces.

Scatter the everything spice croutons evenly over the lettuces. Finish with the freshly grated Parmesan, distributing about 2 tablespoons per serving, or more to taste. Serve immediately so croutons remain crisp.