Pimento Cheese Queso with Toppings Bar

Name: Pimento Cheese Queso with Toppings Bar
Ingredients: 2 tablespoons unsalted butter; 1/2 large red onion, finely chopped; 3 cloves garlic, finely chopped; 1 1/2 teaspoons kosher salt; 1 teaspoon mustard powder; 1/4 teaspoon cayenne pepper; 1/2 teaspoon Louisiana hot sauce; 8 ounces cream cheese, cubed; 1 cup sour cream; 3 cups Pimento Cheese Spread, recipe follows; 2 tablespoons red wine vinegar; 1 jar roasted bell peppers, red and yellow; 1 jar brined cherry peppers or Sweety Pepps; 1 can sliced green olives; 5 green onions, chopped; 1 cup roasted, salted pumpkin seeds; Two 7-ounce jars sliced pimentos, drained; Three 10-ounce bricks sharp Cheddar, finely grated; 1 cup mayonnaise