How to Make It
Preheat a grill to medium-high (400°F to 450°F). Place corn on grate, and grill, covered, until tender and lightly charred, about 12 minutes, turning occasionally. Let cool 10 minutes. Cut corn kernels from cobs.
Place onion, almonds, garlic, smoked paprika, 1 1/2 teaspoons each of the kosher salt and black pepper, and half of corn kernels (about 1 1/3 cups) in bowl of a food processor. In a separate bowl, whisk together apple cider vinegar and 1/4 cup of the olive oil. While drizzling olive oil mixture into corn mixture in processor, pulse until combined with a coarse texture, about 10 times. Set aside, and reserve remaining half of corn kernels.
Toss eggplant with remaining 3 tablespoons oil, 1 teaspoon salt, and 1/2 teaspoon pepper. Place on grate, and grill, uncovered, in batches if needed, until grill marks appear and eggplant is soft, 2 to 3 minutes per side.
Place 1 eggplant slice on each of 8 serving plates. Top with about 1 1/2 tablespoons romesco sauce, 1 tablespoon reserved corn kernels, and a few pieces of torn watercress. Repeat layers twice to make 8 layered stacks.