First prepare a 9x13 pan by lining it with parchment paper and buttering the parchment.
In a large pot over medium heat melt marshmallows and butter stirring frequently until completely melted and smooth.
10 ounces mini marshmallows, ½ cup butter
Remove from heat and add in cake mix and vanilla, stir until well mixed.
1 cup red velvet cake mix, 1 tsp vanilla extract
Add in ½-1 tsp of red gel food coloring and stir to incorporate, add more if necessary to achieve desired color.
red gel food coloring
Add in rice krispies and stir to coat. The mixture will be very thick.
6 cups Rice Krispies cereal
Place mixture in prepared pan and evenly press into place.
Allow to cool completely.
Remove the treats from the pan and cut into 16 even rectangles.
Place white chocolate chips in a microwave safe bowl and microwave them in 30 second increments stirring in between until melted and smooth.
1/3 cup white chocolate chips
Place the melted chocolate in a piping bag or a zip top baggie. Cut off the end or corner and pipe chocolate across each treat.
Allow chocolate to cool.
Store treats in an airtight container.