Preheat oven to 400°F (200°C). Line a baking sheet with parchment paper.
Toss pumpkin cubes with 1 tablespoon olive oil, salt, and pepper. Roast for 25–30 minutes, turning halfway through, until tender and golden.
While pumpkin roasts, heat remaining olive oil in a skillet over medium heat. Add mushrooms and sauté for 5–6 minutes until browned.
Add chopped spinach to the skillet and cook for 2–3 minutes, until wilted. Remove from heat.
In a blender, combine all dressing ingredients. Blend until smooth. Add water to adjust consistency.
On a serving plate, layer roasted pumpkin, sautéed mushrooms and spinach. Sprinkle with crumbled feta.
Drizzle generously with the creamy avocado herb dressing before serving.