First, make the cranberry sauce so it has time to cool. In a small saucepan, combine the cranberries, granulated sugar, and orange juice. Bring to a simmer over medium heat. Cook, stirring often, until the cranberries have burst and the sauce has thickened, about 10-12 minutes. Set aside to cool completely.
Preheat your oven to 350°F (175°C). Line a 12-cup muffin tin with paper liners.
In a medium bowl, whisk together the flour, baking powder, cinnamon, and salt. Set aside.
In a separate large bowl, use an electric mixer to beat the granulated sugar and eggs on medium-high speed until pale and fluffy, about 2 minutes. On low speed, slowly stream in the melted butter and mix until just combined, then mix in the orange zest.
Add half of the flour mixture to the wet ingredients and mix on low until just incorporated. Pour in the milk and mix, then add the remaining flour mixture. Mix only until no dry streaks remain. Do not overmix.
Divide the batter evenly among the 12 prepared muffin cups, filling each about two-thirds full. Bake for 20-22 minutes, or until a wooden skewer inserted into the center of a cupcake comes out clean. Let the cupcakes cool in the tin for 5 minutes before transferring them to a wire rack to cool completely.
While the cupcakes cool, prepare the frosting. In a large bowl, beat the softened cream cheese and softened butter with an electric mixer until smooth and creamy. Sift in the confectioners' sugar and beat on low speed until combined, then increase to medium-high and beat until fluffy.
Reserve 2 tablespoons of the cooled cranberry sauce for garnish. Add the rest of the cooled cranberry sauce to the frosting and beat on low speed until it's fully incorporated and the frosting is a uniform pink color.
Once the cupcakes are completely cool, frost them using a spatula or piping bag. Garnish each cupcake with a small dot of the reserved cranberry sauce and a curl of orange zest, if using.