Preheat oven to 350 degrees F (175 degrees C). Bring the pie crust to room temperature.
Heat the olive oil in a skillet over medium heat; add the onion and cook until onion becomes transparent, about 5 minutes. Combine the spinach with the onion, cover the skillet; turn off the heat, and set aside.
Unroll the crust and press to fit into a 9 inch pie plate. Trim the edges.
Beat the eggs in a large bowl until light colored and frothy. Add the garlic, thyme, basil, cheeses, and spinach mixture, and stir until well blended. Season to taste with salt and pepper. Pour the spinach mixture into the prepared pie crust.
Bake in preheated oven until the top is golden brown, and an inserted tooth pick comes out clean, about 50 minutes.