For cake: Preheat oven to 350. Butter and flour a 12 cup bundt pan. Finely grind the walnuts in a food processor. (Be careful not to turn nuts into a paste!). Sift flour, baking powder and salt into a medium bowl. Using an electric mixer, beat butter and sugar in a large bowl until light and fluffy. Add eggs 1 at a time, beating well after each addition. Beat in maple syrup, maple flavoring and vanilla (batter may looked curdled). Mix in dry ingredients. Fold in ground walnuts.

Pour batter into the prepared bundt pan. Bake cake until top is golden and tester inserted near the center comes out clean, about 1 hour. Transfer pan to a rack; cool cake 10 inutes. Using a small knife, cut around sides and center of pan to loosen cake. Turn cake out onto the rack and cool completely.

Can be prepared 2 days ahead (without glaze). Wrap tightly in foil and store at room temperature.

For glaze. Melt butter with maple syrup and cream in a heavy small saucepan. Remove from heat. Add powdered sugar and whisk until smooth. Cool glaze until slightly thickened, about 15 minutes. Drizzle glaze over pound cake. Arrange walnut halves decoratively o n top of cake. Let cake stand until glaze sets, about 15 minutes.