Applesauce Cake with Brown Butter Maple Buttercream

Name: Applesauce Cake with Brown Butter Maple Buttercream
Prep time: 15 min
Total time: 15 min
Cuisine: American
Ingredients: Nonstick baking spray with flour; 2 1/2 c. all-purpose flour; 1 1/2 tsp. baking soda; 1/2 tsp. baking powder; 1/2 tsp. salt; 2 tsp. apple pie spice; 1 c. granulated sugar; 1 c. packed light brown sugar; 1 1/2 c. chunky applesauce; 1/2 c. vegetable oil; 1/2 c. milk; 2 large eggs; 2 tsp. vanilla extract; 3/4 c. chopped walnuts, optional, plus more for garnish; 2 sticks of butter; 3 1/2 c. powdered sugar; 1/3 c. maple syrup; 1 tsp. vanilla extract; 1/4 tsp. salt; 1/3 c. heavy cream