Fill a large bowl with ice water for an ice bath, and set aside. Whisk egg yolks and sugar until pale yellow and well mixed, about 2 minutes. Bring milk and heavy cream to a simmer in a medium saucepan over medium heat. Reduce heat to low. Add about 1/3 cup of the hot milk mixture to the egg-yolk mixture, whisking constantly, to warm it without cooking it. Then add egg-yolk mixture to the saucepan with the rest of the hot milk.
Cook the mixture over medium heat, stirring constantly with a wooden spoon, until the mixture thickens to the consistency of heavy cream, 4 to 5 minutes. Strain custard into a medium metal bowl, and stir in the peaches. Set the bowl in the ice bath to chill. Once it's cold, pour into ice-pop molds, and freeze.