Fill A Large Pot With Lightly Salted Water And Bring To A Rolling Boil Over High Heat. Stir In The Spaghetti, And Return To A Boil. Cook, Uncovered, Stirring Occasionally, Until The Pasta Is Cooked Through, But Still Firm To The Bite, About 12 Minutes. Drain; Toss With 2 Tablespoons Of The Butter. Melt The Remaining 2 Tablespoons Butter In A Large Skillet Over Medium Heat, And Cook And Stir The Shallots And Mushrooms Until The Mushrooms Are Tender, About 5 Minutes. Stir In The Grape Tomatoes And Garlic, Season With Salt And Pepper, And Cook And Stir Until Tomatoes Are Heated Through, About 3 Minutes. Add The Shrimp, And Cook Until The Shrimp Just Begins To Turn Pink, Stirring Occasionally. Stir In The White Wine And Lemon Juice, Reduce The Heat To Medium-Low, And Simmer Until Shrimp Are Opaque, About 5 Minutes. Stir In The Spinach; Once Spinach Has Wilted, Stir In The Half-And-Half And Parmesan Cheese. Simmer Until All Ingredients Are Heated Through And The Sauce Is Slightly Thickened, About 5 Minutes. Serve Over The Cooked Spaghetti.