Mix the Base. In a mixing bowl, combine softened cream cheese, mayonnaise, garlic powder, onion powder, salt, and pepper until smooth.
Add Cheese & Pimentos. Fold in shredded cheddar cheese and diced pimentos. Stir until everything is well combined.
Adjust Seasoning. Taste and adjust salt, pepper, or add a touch of cayenne for spice.
Serve or Bake. For cold pimento cheese, cover and refrigerate for at least 1 hour to let the flavors meld. For hot dip, transfer to a baking dish and bake at 350°F for 15–20 minutes until warm and bubbly.
Garnish. Sprinkle with chopped green onions or parsley before serving.