Cut the oranges in half around the middle, not from stem to end. Juice the oranges until you get 1/4 cup of orange juice. Use extra juice beyond 1/4 cup and extra orange as you wish.
Use a paring knife to cut around the white pith of the orange halves, then use a spoon or if you have one, I prefer the teeth of a grapefruit spoon, and scrape the insides out, careful not to puncture a hole anywhere in the orange rind.
Add 2 tablespoons of lemon juice to the 1/4 cup of orange juice. Set aside.
Add the heavy cream and sugar to a small sauce pan and bring to a boil, while stirring almost constantly. Once boiling, reduce heat to a simmer and set a timer for 3 minutes. During the 3 minutes, stir the liquid often and scrape the sides of the pan making sure it doesn't create a film. After 3-4 minutes, the mixture should seem thicker and lightly coat a spoon. Add an additional minute if necessary. Remove pan from heat and set a timer for 1-2 minutes.
After the mixture sat for 1-2 minutes, add the orange and lemon juices to the mixture and stir to combine. Pour the mixture through a mesh strainer into a liquid measuring cup.
Place the orange halves staggered on a muffin pan as shown in the photos in the post. Making sure the orange halves are not tilted, pour the mixture into the orange halves almost to the top. You should have enough leftover to pour into a small ramekin.
Refrigerate the possets uncovered for at least 4 hours. 6 hours-overnight is ideal, especially if the refrigerator is being opened a lot. Covering them before they have set will result in condensation dripping down into the posset. They're great as-is, but feel free to garnish them with with mint sprigs and/or fresh raspberries. Enjoy!