To prepare the Plum Tarte Tatin, first prepare the plums by washing them, cutting them in half, and removing the pits. Then, heat a skillet, add 1 cup of sugar and lemon juice. Wait for the sugar to start melting (do not stir), when the sugar is almost melted, you can gently mix it, do not walk away from the stove as the caramel can quickly burn. When the caramel turns golden, add 6 tbsp of unsalted butter. You can remove the skillet from the heat, stir slightly, the butter should dissolve.