Prep: Line a 9x13-inch pan with parchment paper. Spray it lightly with cooking spray.
Red Krispies: In a large pot, over medium-low heat, melt ¼ cup of butter. Once the butter has melted, add in 5 cups of mini marshmallows, stirring often until almost melted.
After that, turn the heat down to low and add in the ½ teaspoon of vanilla extract. Stir to combine. Add in the red food coloring, a little at a time until you get your desired color.
Remove the pot from the heat and stir in 4 cups of rice crispy cereal. The marshmallow cools down quickly, so be prepared to mix in the cereal immediately after removing them from the heat. Stir until the cereal is well coated.
Pour the cereal into the prepared pan and spread it out evenly while pressing down firmly into a layer. Use the back of a buttered spoon to smooth out the top.
White krispies: Repeat the same process for the next batch, use the same amount of butter, mini marshmallows, vanilla extract and rice krispies, just leave out the food coloring as these will be the white layer for the stars. Spread it out evenly on top of the red colored layer and smooth out the top with a spoon.
Blue krispies: Now do the last layer in the same way, but use blue food coloring to complete the patriotic colors. Again, same amount of butter, mini marshmallows, vanilla extract and rice krispies. Then add in the blue food coloring, this is the 3rd and final layer for this treat. Press it firmly over the top of the white layer and smooth out the top.
Cut out stars: Allow the pan of krispie treats to cool completely, until room temperature, before you begin to cut out the stars. They are usually ready within an hour or so.
Using a knife, cut around the edges of the pan if needed to remove the Krispie treats from the baking dish. Peel off the parchment paper and place the rice Krispies onto a cutting board.
Spray the star shaped cookie cutter with some non-stick cooking spray to prevent the marshmallow from sticking to it. Use the star shaped cookie cutter to cut the Krispies into star shapes.
If the cookie cutter can't go all of the way through the layers, then just press an indent onto the top of the rice krispies with the cutter and use a knife to cut out the shapes. Serve & enjoy!