1 pound (3 1/4 cups) all-purpose flour
1 tablespoon coarse salt
4 sticks softened unsalted butter, plus more for pans
2 cups packed brown sugar
1 tsp. pure vanilla extract
1 tablespoon maple extract
3 tablespoon maple syrup
8 large, room-temperature eggs
2 cups toasted, chopped walnuts
For the glaze
1 cup confectioners sugar
4 tablespoons milk
2 tablespoons maple syrup
1/2 cup toasted, chopped walnuts
Preheat oven to 325F. Butter two 5-by-9-inch loaf pans. Combine flour and 1 tablespoon salt in a bowl.
Cream 4 sticks butter and brown sugar with a mixer on high speed until pale and fluffy, for 6-8 minutes. Scrape down sides of bowl. Reduce speed to medium, add vanilla and maple extracts and maple syrup.
Lightly beat eggs, and add to mixer bowl in 4 additions, mixing thoroughly after each and scraping down sides. Reduce speed to low, and add flour mixture in 4 additions, mixing until just incorporated. Fold walnuts into finished batter. Divide batter between pans. Tap on counter to distribute; smooth tops.
Bake until a tester inserted into center of each cake comes out clean, about 60-70 minutes. Let cool in pans completely on wire rack. Mix together the confectioners sugar, milk and maple syrup until smooth. Mix in walnuts. Drizzle it over the cakes.