To make the garlic bread: Preheat the oven to 400 degrees F.
Drizzle the oil over the bread slices. Arrange the bread on a baking sheet. Sprinkle with salt and pepper. Bake until the bread is crisp and golden, about 5 minutes. Immediately rub the garlic cloves over the hot toasts.
To make the aioli: Finely chop the garlic in the food processor. Add the peppers and blend until almost smooth. Blend in the mayonnaise. With the machine running, blend in the oil. Season the aioli, to taste, with salt and pepper. Transfer the aioli to a small bowl. (The aioli can be made 2 days ahead. Cover and refrigerate.)
Spread the aioli over the toasts and serve.