Gently peel the pears, leaving the stems on for presentation. Use a melon baller or small spoon to core them from the bottom, removing the seeds while keeping the pear shape intact.

In a saucepan large enough to hold the pears standing up, combine the red wine, water, granulated sugar, orange slices, lemon slices, cinnamon sticks, cloves, and the split vanilla bean.

Bring the mixture to a simmer over medium heat, stirring until the sugar dissolves completely.

Carefully place the prepared pears into the simmering liquid. They should be mostly submerged. If necessary, place a small piece of parchment paper directly on top of the liquid to keep the pears submerged.

Reduce the heat to low and let the pears gently simmer for 25 to 40 minutes, depending on their size and ripeness. You want them tender when pierced with a knife but not mushy. The liquid will reduce and deepen in color.

Remove the saucepan from the heat. Allow the pears to cool completely in the poaching liquid for at least one hour, or preferably overnight in the refrigerator. This step allows the pears to absorb maximum flavor and color.

While the pears cool or just before serving, combine the softened mascarpone cheese, powdered sugar, and vanilla extract in a small bowl. Whisk until smooth and creamy.

Remove the cooled pears from the liquid. You can serve them warm or chilled. Spoon a generous dollop of the mascarpone cream onto a plate, place a poached pear on top, and drizzle with a spoonful of the reduced poaching syrup.