Combine The Butter And The Olive Oil In A Large Skillet Over Medium Heat. Stir In Pesto, Garlic, And Tomatoes, And Simmer Until The Tomatoes Start To Soften, About 2 Minutes. Season With Red Pepper Flakes And Black Pepper To Taste. Stir The Shrimp Into The Sauce, And Cook Just Until They Turn Pink, 3 To 5 Minutes. Add The Spinach, And Stir Until Wilted, About 1 Minute.