Use fresh marshmallows for the best texture. Older marshmallows can make the bars firmer than you want.

In a large pot, melt the butter over low to medium-low heat. Once melted, add the mini marshmallows and stir until smooth. Stir in a splash of vanilla extract if you want a little extra homemade flavor.

Remove the pot from the heat and quickly stir in the Rice Krispies cereal. For a softer, chewier texture, stir in a small handful of extra whole mini marshmallows right at the end.

Line a 9x13-inch pan with parchment paper, leaving enough overhang to lift the treats out later. Press the mixture gently into the pan. Do not pack it down too firmly or the bars can turn dense.

Let the pan sit at room temperature, or chill briefly, until the treats are set, about 1 hour.

Lift the set block out of the pan using the parchment paper and place it on a cutting board.

Cut into squares or rectangles with a sharp knife. For cleaner cuts, run the knife under hot water, dry it well, and slice.

Melt the red, white, and blue candy melts in separate bowls according to the package directions. Short microwave bursts with frequent stirring work well.

Dip one end or one corner of each bar into the melted candy, or drizzle the colors over the tops for a more polished look. A piping bag or zip-top bag with a tiny corner snipped off makes drizzling especially easy.

While the coating is still wet, add sprinkles. Let the candy coating set fully before serving.