Cook the Pasta: Boil the small shell noodles according to the package directions until al dente. Drain and rinse under cold water to stop the cooking process and cool the pasta quickly.
Chill the Pasta: For the best flavor and texture, place the noodles in the refrigerator for about 30–60 minutes to cool completely. Pasta salad is always best when served cold.
Prep the Ingredients: While the pasta chills, dice the cheese, cucumber, pickles, and green onions. Halve the cherry tomatoes and prepare your choice of meat — slice pepperoni and salami into bite-sized pieces or drain the canned shrimp if using.
Mix It All Together: In a large mixing bowl, combine the chilled noodles with the diced vegetables, cheese cubes, and meats. Stir gently to combine without breaking the noodles.
Make the Dressing: Add a generous amount of mayonnaise and a small squeeze of mustard to the mixture. Season with salt and pepper to taste. Stir until everything is evenly coated and creamy.
Chill Before Serving: For the best flavor, refrigerate the pasta salad for at least 1 hour before serving. This allows the ingredients to meld together and the dressing to thicken slightly.
