Cooking spray
Spray the bottom and sides of a metal or glass loaf pan with cooking spray. Line the pan with a sheet of parchment paper with extra hanging over the long sides. Press the parchment paper into the bottom and up the sides of the pan and crease the extra along the edges, forming handles (this will make it easy to lift the finished candy out of the pan later). Spray the parchment with more cooking spray and set the pan aside.
1 ¼ cups cold water, 2 tablespoons powdered gelatin, ¾ cup granulated sugar
Add the water to a large microwave-safe bowl. Sprinkle the gelatin over the top and let sit until softened and gooey, about 5 minutes. Add the granulated sugar to the bowl and whisk until well combined.
Transfer the bowl to the microwave and cook on high power for 1 minute at a time, whisking in between each minute, until the sugar has dissolved and the mixture is bubbling and has turned clear, 4 to 6 minutes. Be careful when whisking, as the bowl will be hot and the mixture may bubble up and foam.
½ cup powdered sugar, ¼ cup cornstarch, ⅛ teaspoon cream of tartar
Fold a clean kitchen towel in half and set it on the counter next to the microwave. Use oven mitts to carefully remove the bowl from the microwave (it will be VERY hot!) and set it on the towel. Add the powdered sugar, cornstarch, and cream of tartar to the bowl and whisk until well combined.
Return the bowl to the microwave and heat until bubbly and foamy throughout, 1 to 3 minutes. Open the microwave door and let the mixture cool and calm down a bit, 1 to 2 minutes; the mixture will look thick and syrupy.
1 tablespoon lemon juice, 1 teaspoon rose water, Red or pink food coloring
Use oven mitts to carefully remove the bowl from the microwave (it will be VERY hot!) and set it on the towel. Add the lemon juice, rose water, and a couple of drops of food coloring, if using, and whisk until evenly combined.
Pour the mixture into the greased, parchment-lined loaf pan. Let cool slightly, about 15 minutes. Cover the pan loosely with plastic wrap and transfer to the refrigerator to chill until firm and set, at least 1 hour and up to overnight.