Place oven racks in upper and lower thirds of oven. Preheat to 425 degrees F. Line one large baking sheet with parchment paper.
Place cauliflower in a food processor. Process until finely grated. Transfer to a microwave-safe bowl. Cover loosely and microwave on High for 3 minutes. Let cool slightly. Transfer the cauliflower to a clean kitchen towel and wring out excess moisture. Return to the bowl and stir in Cheddar, egg, pepper and salt until thoroughly combined. Using about ¼ cup of the cauliflower mixture for each, create eight 3-inch squares on the prepared baking sheet.
Bake until the toasts are browned and crispy around the edges, 22 to 25 minutes.
