Vegan Spanakopita (Greek Spinach Pie) - From the Comfort of My Bowl

Name: Vegan Spanakopita (Greek Spinach Pie) - From the Comfort of My Bowl
Cuisine: European, Greek, Mediterranean
Ingredients: 2 lbs fresh spinach; 1 tbsp extra virgin olive oil; 1 medium onion; 2 lbs vegan feta, homemade or storebought, drained; 2 bunches fresh dill; ½ lemon; 1 tsp black pepper, or to taste; Salt, to taste; 4 tbsp cornstarch; 1 lb phyllo dough, (See Notes); 1 cup extra virgin olive oil, or melted vegan butter