For candy hearts, first line a baking sheet with parchment paper and preheat the oven to 50 °C.
Pour granulated sugar into a large bowl. Gradually add cold water by the teaspoon (!) and stir into the sugar with a wooden spoon. The sugar should feel like damp sand and should be able to be pressed together with the wooden spoon to form a homogeneous mass. (If in doubt, just try it out and add a little more water or sugar if necessary).
Line the work surface with a sheet of baking paper. Spread sugar mixture on it with your hands and press into a disk about 1 cm high. Using a cookie cutter, cut out small hearts and carefully place them on the prepared baking sheet.
Put the tray into the preheated oven and let the sugar hearts dry for 50-60 minutes.