Heat butter in a pan and fry the walnuts until it's roasted, for about 5 minutes. Stir in the maple syrup and salt; cook for 1 more minute. Spread on a baking sheet to cool completely.

Preheat oven to 350F/180C for 15 minutes. Line two 8 or 9 inch round cake pans with parchment paper.

In a medium size bowl sift together the flour, baking powder, baking soda and salt; set aside.

In a large bowl cream together the butter and sugar until light and creamy. Beat in the maple syrup, kefir and maple extract too.

Add the flour mix to the creamed sugar mixture alternately with milk, beating after each addition.

Stir in ½ cup of candied walnuts to the cake batter.

Divide the batter among the 2 pans (approx. 2 and ½ cups of batter per pan) and bake it for 15-20 minutes or until a toothpick inserted in the center of the cake comes out clean.

Cool in pan for 10 minutes before moving to wire racks. Cool completely before frosting.

Combine ¼ cup sugar and ½ cup water and bring to boil for about 3 minutes. Let cool.

Once the cakes have cooled enough, poke holes with wooden skewers and brush the cake with the sugar syrup generously.

In a large bowl beat butter until creamy. Beat in the sugar, 2 tablespoons of syrup, 2 tablespoons of milk, maple extract and salt to reach the desired consistency.

Place one layer on a serving plate. Spread with 1 cup of frosting. Sprinkle ½ cup of candied nuts over the frosting and drizzle a tablespoon of maple syrup. Top it with the 2nd layer and frost the top and sides of the cake. Sprinkle the remaining ½ cup of walnuts ont he top of the cake and drizzle another tablespoon of maple syrup on top.