Preheat the oven to 375 degrees. Spread the tortilla chips in a single layer on a large baking sheet.

In a skillet over medium heat, warm the black beans with the chili powder and cumin for 3 minutes until heated through. Spoon the beans evenly over the chips.

Sprinkle the shredded cheddar cheese over the beans and chips. Bake for 8 to 10 minutes until the cheese melts and bubbles.

While the nachos bake, stir the sour cream and milk together in a small bowl until smooth. Transfer the mixture to a zip-top bag and snip off one corner.

Remove the nachos from the oven. Pipe the sour cream in concentric circles on top of the cheese, then drag a toothpick from the center outward to form a web pattern.

Slice 4 olives in half for the spider bodies. Cut the remaining olives into thin strips for legs. Place one half-olive body on the web and arrange 8 strips as legs around it. Repeat with the rest of the olives.