- Nonstick vegetable oil spray
- 2 cups all purpose flour
- 2 teaspoons baking powder
- 1/2 teaspoon baking soda
- 1/4 teaspoon salt
- 1 1/3 cups sour cream
- 1/4 cup pure maple syrup
- 1/2 cup walnuts, toasted, chopped
- 1/4 cup plus 1 1/3 cups maple sugar
- 1/4 teaspoon ground cinnamon
- 13 tablespoons butter, cut into pieces, room temperature
- 2 large eggs
- 2 teaspoons vanilla extract
- 1 1/3 cups powdered sugar
- 3 tablespoons sour cream
- 1 tablespoon pure maple syrup
- 1 1/2 teaspoons fresh lemon juice
- 1 teaspoon vanilla extract
- 1/2 teaspoon grated lemon peel
- Whipped cream
- Preheat oven to 350°F. Butter 9-inch-diameter Bundt pan, then spray with nonstick spray. Combine flour, baking powder, baking soda, and salt in medium bowl. Whisk sour cream and maple syrup in another medium bowl. Mix walnuts, 1/4 cup maple sugar, and cinnamon in small bowl.
- Using electric mixer, beat butter and remaining 1 1/3 cups maple sugar in large bowl until fluffy. Gradually beat in eggs and vanilla, occasionally stopping to scrape down sides of bowl. Add flour mixture in 3 additions, alternating with sour cream mixture in 2 additions. Transfer 2/3 of batter to prepared Bundt pan. Sprinkle with walnut mixture. Pour remaining batter into pan.
- Bake cake until tester inserted near center comes out clean, about 55 minutes. Cool 20 minutes. Turn out cake onto rack; cool completely.
- Whisk first 6 ingredients in medium bowl to blend. Let stand until thickened, about 30 minutes. Pour glaze over cake. (Can be made 1 day ahead. Cover and keep at room temperature.)
- Serve cake with whipped cream.