Preheat oven to 400°F.
Line a large, rimmed baking sheet with parchment paper or a Silpat® baking mat. Set aside.
Place 2 tablespoons olive oil in a large skillet, Heat over medium heat.
When hot and shimmering, add onion and celery. Season with salt and black pepper, to taste. Cook, stirring occasionally, until the onion is soft and translucent, about 4 - 5 minutes.
Add another tablespoon of olive oil to the skillet.
Add garlic and eggplant. Cook, stirring occasionally, until the eggplant begins to cook down, about 6 - 7 minutes.
Add tomatoes, tomato paste, passata, vinegar, capers, green olives and raisins. Stir to combine.
Cover skillet with a lid.
Reduce heat to low and simmer gently for 15 minutes.
While caponata is simmering, lightly brush each cod fillet with the remaining olive oil.
Season with salt and black pepper on both sides, to taste.
Place the fillets on prepared baking sheet.
Place sheet in pre-heated oven.
Roast until fish turns opaque and flakes easily with a fork, about 12 - 13 minutes. (Check fish after 10 minutes. Do not overcook)
Remove lid from skillet. Stir in two tablespoons each fresh parsley and toasted almonds into the caponata. Taste and adjust seasonings, as desired.
Spoon caponata into individual serving plates or shallow bowls.
Garnish with remaining parsley and almonds.
Place a fish fillet atop each dish.
Serve.