Fill a large bowl about halfway full with ice water. Get a medium bowl ready with a sieve that rests securely inside of it, and set aside.
Add 1 ⅔ cup whole milk, ½ cup skim milk powder, and ¾ cup granulated sugar to a medium saucepan and whisk until combined. Add the 1 ⅔ cup heavy (whipping) cream and whisk. Place 3 large egg yolks in a medium heat-proof bowl on a heat-proof surface.
Add 1 cup cinnamon heart candies and over medium-high heat, heat the mixture while stirring constantly until the cinnamon hearts melt completely. At one point the candies will start clumping together and will want to stick to the bottom of the pan—just keep heating and stirring until they all melt. This will take about 8–10 minutes.
Slowly pour about half of the hot cream mixture over the egg yolks while whisking constantly, then return everything to the saucepan. Continue heating over medium heat while stirring until slightly thickened, about 2–3 minutes. Just note that his won't get as thick as a traditional custard.
Pour the mixture through the sieve into the medium bowl you prepped earlier. Place the medium bowl into the ice-water bath, and stir it occasionally until it cools down to room temperature. Remove the bowl from the ice-water bath and press a piece of plastic wrap directly on the surface, and refrigerate until completely cool (about 2 hours). Place an empty food-safe container in your freezer, large enough to store 1 ½ times the size of the ice cream mixture (it will expand as it gets churned and frozen).
Freeze according to your ice cream maker's instructions. Alternatively, you could spread the ice cream mixture out on a baking sheet and place that in your freezer, and give it a stir every hour or so until it has the texture of soft serve.
Transfer the churned ice cream to the frozen container, and freeze at least 8 hours or overnight for a scoopable texture. Enjoy!
