Sprinkle some of the roughly chopped Reeses pieces into the bottom of the molds. Reserve the rest for later.
In a large bowl, beat together the egg yolks and sugar until pale, about 3 minutes. Set this bowl over a pot of simmering water and continue to whisk until the mixture has thickened, about 4 minutes. Be careful that the bottom of the bowl does not touch the water in the pot.
After the mixture has thickened, remove from the heat and continue to whisk for one more minute. Set aside.
In a clean, large bowl, whisk together the egg whites until you have stiff peaks. In another bowl, beat the cream until it reaches the soft peak stage. Fold 1/3 of the stiffened egg whites into the thickened egg yolk and sugar mixture. Now add 1/3 of the whipped cream. Continue folding in the whites and cream, alternating until everything has been added. Gently fold in the remaining chopped Reeses pieces and peanuts. Spoon into your molds. If adding popsicle sticks, dip them in the peanut butter and then place in the center of each filled mold. Transfer to the freezer and leave to set for at least 5 hours.
If you don’t have popsicle molds, small paper cups are a great alternative. Simply pour in the prepared mixture and then insert a wooden popsicle stick before freezing.