Remove Kellogg’s Rice Krispie Treat bars from wrappers and set aside.
With a rolling pin, roll out the yellow fondant to about 1/8″ thick. Dust a bit of powdered sugar on work surface and rolling pin if the fondant is sticky.
Using the 2″x1.75″ rectangular cookie cutter, cut out the fondant into 8 rectangles.
Place a small amount of red frosting on top of each Rice Krispie Treat and lay one yellow fondant rectangle to cover the top.
Using a paring knife, cut a small square out of the corner of each fondant-covered Rice Krispie Treat to resemble the shape of a school bus.
Using the rolling pin, roll out the black fondant to about 1/8″ thick. With the mini round cookie cutter, cut out 16 circles. Apply a little bit of frosting on the back of each round black fondant and adhere to the school bus to resemble the school bus wheels.
Using the paring knife, cut out 24 small rectangles from the leftover black fondant. Apply a little bit of frosting on the back of each small rectangle and place 3 on each of the school bus to resemble windows. Use toothpicks to secure, if needed.
Attach the small round plastic tip of the Wilton Red Icing and use the icing to make a red circle on the side of each bus to resemble lights.