For pears: Preheat oven to 400°F. Combine first 6 ingredients in 13x9x2-inch glass baking dish; toss to blend. Cover dish with foil and bake until pears are tender, stirring occasionally, about 40 minutes. Uncover. Mix in cranberries and bake until cranberries are tender but still hold shape, about 15 minutes. Cool fruit mixture. Maintain oven temperature.
For biscuits: Line baking sheet with parchment paper. Blend flour, cornmeal, 3 tablespoons sugar, baking powder, salt and baking soda in processor. Add butter; using on/off turns, blend until butter is cut into pea-size pieces. Add buttermilk; using on/off turns, blend until dough comes together. Pat out dough on floured surface to scant 3/4-inch thickness. Using 2 3/4-inch-diameter cutter, cut out 4 biscuits. Gather scraps; pat out to scant 3/4-inch thickness. Cut out 2 more biscuits.
Arrange biscuits on prepared sheet; brush with beaten egg. Bake until golden brown and tester inserted into center comes out clean, about 15 minutes.
Beat cream and powdered sugar in medium bowl to stiff peaks. Cut biscuits horizontally in half. Place bottoms on plates. Top each with pear mixture, whipped cream, then biscuit tops.