Line a standard-sized loaf pan with foil, extending the sides of the foil over the edges of the pan. Mist the foil lightly with cooking spray, for added cake insurance.
Place two PopTarts (unwrapped, of course), horizontally side by side in the bottom of the foil-lined pan. If two struggle to fit, cut one of them to fit.
In a large bowl, gently fold together the dry pudding mixes and the Cool Whip containers until blended. Work quickly since they will solidify on you pretty fast. Spread about half of the mixture on top of the first layer of PopTarts.
Lay down another layer of PopTarts, and continue to spoon the mixture over the layers. I built up to four layers in my cake. Finally, top the remaining layer of PopTarts with the remaining pudding mixture.
Coat the top of the cake with sprinkles and blueberries. Freeze the cake for about 4 hours (overnight preferred) before cutting into slices. Serve immediately!
Recipe by The Domestic Rebel at https://thedomesticrebel.com/?p=5139