Hydrate the Batter: In a medium bowl, whisk chickpea flour, water, 1 tbsp olive oil, garlic, oregano, pepper, and salt until smooth. Cover and rest 1 hour at room temperature.
Preheat the Pan: Adjust rack to middle and heat oven to 450°F (230°C) about 15 minutes before baking. Place a 10-inch cast-iron skillet or a 9-inch metal cake pan in the oven to preheat.
Prep the Ribbons: Using a vegetable peeler, shave zucchini and yellow squash lengthwise into ribbons. Spread on a clean towel, let stand 10 minutes, then pat very dry. Toss ribbons with 1 tbsp olive oil.
Bake the Foundation: Carefully remove the hot pan. Add 1 tbsp olive oil, swirl to coat. Whisk the batter briefly and pour into the pan (it should sizzle). Bake 10–12 minutes until edges are golden and pulling away and the center looks set (a spatula should lift the underside easily).
Assemble the Garden Layer: Remove pan from oven. Scatter spinach over the hot socca to wilt. Spread passata evenly. Arrange squash ribbons, artichoke hearts, and cherry tomatoes. Drizzle remaining 1 tbsp olive oil over the vegetables.
Final Bake: Top with feta and pumpkin seeds. Return to oven and bake 5–6 minutes until vegetables are tender-crisp and feta slightly softened.
Finish & Serve: Remove from oven. Garnish with thyme and a few grinds of black pepper. Rest 2–3 minutes, slide onto a board, slice into 3 portions, and serve warm.