Preheat your oven to 375°F (190°C) and line a small baking sheet with parchment paper.
In a non-stick skillet over medium heat, sauté the diced yellow onion and minced garlic until translucent, about 3 minutes.
Add the ground turkey to the skillet, breaking it up with a spatula, and cook until browned and fully cooked through.
Add the fresh spinach to the pan in batches, stirring until completely wilted; remove from heat and let the mixture cool for 5 minutes.
Place the turkey and spinach mixture into a fine-mesh sieve and press firmly with a spoon to remove all excess moisture to prevent a soggy crust.
In a mixing bowl, whisk the egg and then fold in the turkey-spinach mixture, crumbled feta cheese, chopped fresh dill, sea salt, and black pepper.
Lay one sheet of phyllo dough on a clean surface, lightly brush with half of the olive oil, and place the second sheet directly on top.
Place the spinach and turkey filling in the center of the phyllo sheets, then fold the edges over the filling to create a rectangular packet.
Brush the top of the phyllo with the remaining olive oil and bake for 20-25 minutes until the pastry is deeply golden brown and flaky.
Allow the pie to rest for 5 minutes before slicing and serving.