PreparationFor cake: Preheat oven to 350°F. Butter and flour 12-cup Bundt pan. Finely grind walnuts in processor. Sift flour, baking powder and salt into medium bowl. Using electric mixer, beat butter and sugar into 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 extract (butter may look curdled). Mix in dry ingredients. Fold in ground walnuts. Pour batter into prepared pan. Bake cake until top is golden and tester inserted near center comes out clean, about 1 hour. Transfer pan to rack; cool cake about 10 minutes. Using small knife, cut around sides and center of pan to loosen cake. Turn cake out onto rack and cool completely. (Can be prepared 2 days ahead. Wrap tightly in foil and store at room temperature.) For glaze: Melt butter with maple syrup and cream in 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 on top of cake. Let cake stand until glaze sets, about 15 minutes.
PreparationFor cake: Preheat oven to 350°F. Butter and flour 12-cup Bundt pan. Finely grind walnuts in processor. Sift flour, baking powder and salt into medium bowl. Using electric mixer, beat butter and sugar into 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 extract (butter may look curdled). Mix in dry ingredients. Fold in ground walnuts. Pour batter into prepared pan. Bake cake until top is golden and tester inserted near center comes out clean, about 1 hour. Transfer pan to rack; cool cake about 10 minutes. Using small knife, cut around sides and center of pan to loosen cake. Turn cake out onto rack and cool completely. (Can be prepared 2 days ahead. Wrap tightly in foil and store at room temperature.) For glaze: Melt butter with maple syrup and cream in 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 on top of cake. Let cake stand until glaze sets, about 15 minutes.