Heat the oven to 400°F and line a baking sheet with parchment paper.
Place the bagel halves cut side up on the sheet. Spread 1 tablespoon of pizza sauce on each half, leaving a small amount of sauce aside for the web design.
Sprinkle about 1/4 cup of mozzarella cheese over the sauce on each bagel half.
Use a small spoon or squeeze bottle to add thin lines of the remaining pizza sauce in concentric circles on the cheese.
Drag a toothpick from the center outward through the circles to form a web pattern.
Add a few black olive slices to each bagel to create spider shapes.
Bake for 8 to 10 minutes until the cheese is melted and the edges are lightly golden. Serve warm.