Cook the bacon until crispy, then let it cool on a paper towel before crumbling it into small pieces. Toast the slivered almonds in a dry skillet over medium heat until golden and fragrant, being careful not to burn them.

In a mixing bowl, combine the shredded cheddar cheese, toasted slivered almonds, crumbled bacon, and finely chopped green onions. If using, add the garlic powder and black pepper. Stir to mix well.

Add the mayonnaise to the mixture and stir until all the ingredients are well coated and the dip is thoroughly combined.

Cover the bowl with plastic wrap and refrigerate the dip for at least 1 hour to allow the flavors to meld together. The dip can also be made a day ahead, which often enhances its taste.

Serve the Neiman Marcus Dip chilled, with an assortment of crackers, sliced baguette, or vegetable sticks for dipping.