In a large pot, over low heat, melt the butter. Once melted, add in the mini marshmallows and continue cooking and stirring until the marshmallows are completely melted and smooth.
1/2 cup (1 stick) butter, 8 cups mini marshmallows
Next, stir in the vanilla extract and mix until it's combined well.
1½ teaspoons vanilla extract
Turn off the heat and stir in the Rice Krispie cereal until combined well and all the cereal is coated.
8 cups Rice Krispies cereal
Let the rice krispie treat mixture sit and cool for 2-3 minutes before adding in the candy.
Stir in 1/2 cup of m&m's, 1/2 cup of candy corn, and 2 tablespoons of the sprinkles. Stir gently to combine.
1/2 cup Halloween M&M's, 1/2 cup candy corn, 2 tablespoons Halloween sprinkles
Press the Rice Krispie mixture into the prepared pan. Be careful not to heavily press or smash the Rice Krispie treats into the pan or else they will tough and dry.
Press the garnish/decorating candy over top. You may have to gently press the candy into the bars to get them to stay.
1/2 cup Halloween M&M's, 1/2 cup candy corn
Melt the almond bark or melting wafers in the microwave according to the package directions. Place the melted chocolate into a sandwich Ziploc bag and snip the bottom corner off. Drizzle the melted chocolate over top the bars and immediately add the sprinkles and press the candy eyeballs into the chocolate lines.
2 blocks white almond bark, 1 tablespoon Halloween sprinkles, edible candy eyeballs
Allow the krispie treat bars to sit at room temperature for about 15-20 minutes for the chocolate drizzle to set.
Cut into squares and serve!