Trim stem end of the eggplant so it remains attached, leaving the base intact. Score the eggplant into ½"–¾" slices, cutting almost through but not separating the bottom so the slices stay fanned.

Sprinkle salt between all the slices (use about 1–2 tsp total, distributing evenly). Let rest for 10 minutes to draw out moisture.

Rinse the salted eggplant under cold water, rinsing between the layers to remove excess salt. Pat thoroughly dry with paper towels or a clean kitchen towel, getting between slices as best you can.

Preheat oven to 400°F (200°C). Lightly oil a baking sheet or line with parchment.

Brush or drizzle the outside and between slices with 1–2 Tbsp olive oil. Season lightly with additional salt and pepper if needed.

Tuck alternating slices of mozzarella and tomato into each cut (mozzarella, tomato, mozzarella, etc.) until the eggplant is filled.

Spoon small amounts of pesto between some of the layers, spreading gently so each pocket gets flavor (reserve about 2–3 Tbsp for serving).

Sprinkle the top and exposed layers with oregano, a little more salt and pepper if desired, and scatter the chopped parsley over and between layers.

Place on the prepared sheet and bake 35–40 minutes, until eggplant is tender, cheese is melted and top is lightly golden. If the top browns too quickly, tent with foil.

Remove from oven, let rest 5 minutes. Drizzle additional pesto over the top and sprinkle extra chopped parsley.

Serve warm as a main or side: as-is, with toasted bread, or alongside cooked linguine.