Combine whole milk, heavy cream, and granulated sugar in a medium saucepan over low heat. Stir occasionally—not constantly—because you're gently dissolving sugar, not making whipped cream. I personally watch for when the sugar disappears completely and the mixture stops clinking against the pan bottom, roughly 5 minutes.

Remove from heat and add fresh orange juice, orange zest, vanilla bean paste, and salt. Whisk until the zest distributes evenly and no vanilla paste clumps remain. This cooling window is why the mixture doesn't curdle—cold juice hitting cold cream stays smooth, whereas hot would separate it.

Stir in the corn syrup and 1/2 cup water using a fork pressed against the pan's side. The syrup dissolves into liquid form rather than clumps, which is when you know it's incorporated properly. I taste here to check the orange flavor intensity, adjusting with a tiny squeeze of lemon if it feels flat.

Swirl in the orange marmalade using a rubber spatula by folding it gently from bottom to top. You want distinct ribbons rather than completely blended mixture—those streaks become the visual magic in the frozen pops. Let the base cool to room temperature, about 20 minutes.

Pour the mixture into popsicle molds, leaving roughly 1/2 inch space at the top for expansion. This matters because the mixture expands as it freezes, and overfilled molds push the sticks upward. I've learned this the hard way after messy freezer incidents, so trust this spacing detail.

Insert wooden sticks and freeze for at least 4 hours, though overnight is genuinely better because it ensures everything sets completely. The longer freeze allows the corn syrup to do its anti-crystal work thoroughly. After 8 hours, run warm water over the outside of the molds for 30 seconds to loosen the pops before pulling.