Hot Reuben Dip in a Pumpernickel Bread Bowl

Name: Hot Reuben Dip in a Pumpernickel Bread Bowl
Ingredients: 1/2 cup mayonnaise; 3 tablespoons ketchup; 2 tablespoons finely chopped dill pickle; Kosher salt and freshly ground pepper; 3 cups grated Swiss cheese (about 9 ounces); 2/3 cup sauerkraut, drained, rinsed and roughly chopped; 4 ounces cream cheese, at room temperature; 4 ounces chopped sliced pastrami (about 1 cup); 1 round or oval loaf pumpernickel bread (about 8 inches); Extra-virgin olive oil, for drizzling; Crackers and/or crudites, for serving