Preheat oven to 350°F Butter 9-inch diameter springform pan. Wrap outside of pan with foil.
Mix cornmeal, chopped walnuts, baking powder and salt in small bowl.
Beat butter in large bowl until light and fluffy. Gradually beat in honey, then 3/4 cup sugar. Stir in cornmeal mixture (batter will be very stiff).
Using clean dry beaters, beat egg whites in medium bowl to soft peaks. Gradually add remaining 2 T sugar and beat until stiff but not dry. Fold whites into batter in 3 additions. Transfer batter to prepared pan. Place walnut halves around top edge of cake, spacing evenly.
Bake until cake is deep golden on top, pulls away from sides of pan and tester inserted near center comes out clean, about 45 minutes. Cool cake in pan on rack (cake will fall in center as it cools). (Can be prepared 1 day ahead. Cover adn let stand at room temperature.).
Run sharp knife around pan sides to loosen cake. Release pan sides. Cut cake into wedges and serve.