In a small saucepan, whisk together the fresh orange juice, granulated sugar, and cornstarch until smooth. Bring to a simmer over medium heat, stirring constantly, until the mixture thickens slightly, about 3-5 minutes. Remove from heat, stir in orange food coloring (if using), and let cool completely. Once cool, cover and refrigerate until thoroughly chilled, at least 2 hours or overnight.

In a large bowl, whisk together the heavy cream, whole milk, granulated sugar, vanilla extract, orange zest, and a pinch of salt until the sugar is fully dissolved.

Cover the bowl with plastic wrap and refrigerate the ice cream base for at least 4 hours, or preferably overnight, until it is very cold. This step is crucial for achieving a smooth texture.

Pour the chilled ice cream base into your ice cream maker and churn according to the manufacturer's instructions, usually 20-25 minutes, until it reaches a soft-serve consistency.

Transfer half of the freshly churned ice cream into a freezer-safe airtight container. Drizzle about half of the chilled orange swirl over the ice cream. Gently swirl it in with a knife or spoon, being careful not to overmix. Add the remaining ice cream, then drizzle with the rest of the orange swirl and repeat the gentle swirling process.

Cover the container tightly and freeze for at least 4-6 hours, or until the Orange Creamsicle Ice Cream is firm and scoopable.