Greek-Style Quinoa Pilaf

2 tablespoons butter, divided

1 small yellow onion, finely chopped 

1 cup cherry tomatoes, halved

1 cup rinsed quinoa 

1 1/4 cups water 

5 cups baby spinach (5 ounces) 

1/2 cup crumbled feta

Salt and pepper 

In a large deep skillet, melt 1 tablespoon butter over medium heat. Add onion and cook until beginning to soften, about 2 minutes. Add tomatoes and cook until soft, about 4 minutes more. Add quinoa and toast 1 minute. Add remaining butter and water and bring to a boil. Reduce heat to medium low, cover and simmer until water is absorbed, about 13 minutes. Stir in spinach and feta, then season with salt and pepper.