In a large saucepan combine the water, dates, and pears. Bring to boiling; reduce heat. Cook, covered, about 15 minutes or until fruit is tender and most of the liquid is absorbed. Mash with a potato masher, fork, or immersion blender until as smooth as possible. Stir in baking soda; set aside.
Preheat oven to 350 degrees F. Grease an 8x8x2-inch baking pan; set aside. In a small bowl combine flour, baking powder, salt, and nutmeg; set aside. In a large bowl combine brown sugar and butter. Beat with an electric mixer on medium speed about 1 minute or until combined. Beat in eggs, one at a time, and vanilla. Stir in date-pear mixture. Stir in flour mixture just until combined. Pour batter into prepared baking pan.
Bake in the preheated oven for 40 to 45 minutes or until a toothpick inserted near the center comes out clean. Place pan on a wire rack. Immediately use a long skewer to prick top of cake all over. Spoon the portion of Toffee-Pear Sauce without pears over cake. Bake for 3 minutes more. Cool on the wire rack for 10 minutes. Serve warm with the portion of Toffee-Pear Sauce with pears.