Heat oven to 425°F. In 10-inch skillet, heat oil and 1 tablespoon butter over medium heat. Add onion and garlic; cook 8 to 10 minutes, stirring occasionally, until golden brown. Stir in spinach, thyme, 1/2 teaspoon of the salt and 1/2 teaspoon of the pepper; cook 1 to 2 minutes, stirring frequently, until spinach is wilted. Cool 5 minutes.