For Pears: Add lemon juice to large bowl of cold water. Peel pears, leaving stems intact. Use melon baller to remove core through bottom end. Add pears to bowl of water. Bring Port, sugar, ginger, cinnamon sticks and vanilla bean to boil in heavy large Dutch oven over high heat, sturring until sugar dissolves. Reduce heat to medium-low and simmer syrup 10 minutes. Drain pears and add to syrup. Simmer until tender, turning frequently, about 20 minutes. Using slotted spoon, transfer pears to large container and stand upright. Boil syrup until reduced to 1 3/4 cups, about 18 minutes. Pour syrup over pears. Cover and chill. (Can be prepared 1 day ahead.) For Cake: Position reack in center of oven and preheat to 350F. Butter 9x13x2-inch pan. Dust pan with flour; tap out excess. Mix chopped ginger and 2 1/2 tablespoons sugar in small bowl. Let stand until syrup forms, stirring frequently, about 30 minutes. Mix flour, baking soda, and spices in medium bowl. Using electric mixer, beat butter and brown sugar in large bowl until fluffy. Add molasses, coffee and chopped ginger mixture and beat until blended (mixture may look curdled). Add eggs 1 at a time, beating well after each addition. Reduce speed to low. Add dry ingredients alternately with buttermilk, beginning and ending with dry ingredients and beating after each addition until just blended. Transfer bater to prepared pan. Bake until tester inserted into center comes out clean, about 30 minutes. Transfer to rack and cool in pan. (Can be prepared 8 hours ahead. Cover and let stand at room temperature.) For Cream: Beat whipping cream, powdered sugar, vanilla extract and ground ginger in large bowl until firm peaks form. (Can be prepared 3 hours ahead. Cover and refrigerate. Rewhip if necessary.) Cut gingerbread into 2 1/2 inch squares. Place 1 cake square and 1 pear on each of 8 plates. Spoon some syrup over each pear. Spoon dollop of whipped cream alongside.