Presoak a clay pot, top and bottom, in water for 10 minutes.
Core the pears without breaking through the bottoms. Put
Cover the pot and place it in a cold oven.
Set the oven temperature at 450 degrees.
Bake for 45 to 50 minutes. (Test after 45 minutes by pricking the pears with a toothpick; the pears should be soft, though not mushy.)
Cool a metal bowl in the freezer, then whip the cream in it until slightly stiff. Add the remaining teaspoon vanilla. Continue whipping until the cream just comes to a constant peak, but is not too stiff. Top the pears with whipped cream and serve.