Heat oil in a large frying pan over medium heat. Add the onion and cook until softened; about 5 minutes. Add garlic, cooking until fragrant, about 30 seconds more. Deglaze the hot pan with the wine, scraping up any brown bits. Stir in the spinach, olives, pine nuts, chile flakes, salt and pepper.
3 tbsps. olive oil, 1 cup chopped yellow onion, 1 tbsp. minced garlic, 1/2 cup dry white wine, 5 oz. fresh baby spinach, 1 cup pitted Kalamata olives, 1 cup pine nuts, 1 tsp. red pepper flakes, 1/2 tsp kosher salt, 1/2 tsp coarsely ground black pepper