Spread the refried beans evenly across the bottom of an 8-inch pie plate or shallow serving dish.
Cook the ground beef in a skillet over medium heat until browned. Drain any excess fat, then stir in the taco seasoning and 2 tablespoons of water. Simmer for 2 minutes and let cool slightly.
Spoon the seasoned beef over the beans in an even layer.
Sprinkle the shredded cheese over the beef.
Spread 3/4 cup of the sour cream over the cheese to form the next layer.
Add the mashed avocado in an even layer, followed by the salsa.
Scatter the sliced black olives on top.
Place the remaining 1/4 cup sour cream in a small plastic bag, snip off one corner, and pipe concentric circles over the dip. Drag a toothpick from the center outward in several spots to create the web pattern. Use one olive half to form a spider in the center if desired.
Serve with tortilla chips for dipping.