Scrape sides of bowl and mix briefly. Pour batter into prepared bundt pan, level the top and bake 55 min-1 hour 5 minutes or until toothpick comes out clean after being inserted. Remove from oven and cool in the pan 15 minutes. Poke small 1 inch deep holes into the top of the cake and spoon 1/3 of the sweetened condensed milk into the holes and over the visible cake. Let this soak in 15 minutes and then turn cake out of pan onto cooling rack. Run a knife along the sides to ensure the cake will come out of the pan easily.

Poke more small holes {about 2 inches deep} into the top of the cake and spoon the remaining sweetened condensed milk into the holes and over the entire cake so it is completely covered. Let cake sit 1-2 hours so sweetened condensed milk can be absorbed. Carefully remove cake from cooling rack and place onto cake stand.

For the frosting, whip butter and maple syrup together until combined. Stir in vanilla and powdered sugar until completely smooth. Spread frosting over top of cake and down the sides slightly. Top with chopped walnuts. Store in refrigerator until ready to serve.

Instructions for 9×13 pan: Bake at 325 for 40-50 minutes. Cool 15 minutes, poke holes into it and pour the entire can of sweetened condensed milk over top. Place into the refrigerator until sweetened condensed milk has been absorbed. Make frosting as listed above, but fold in 1 cup plain whipped cream. Frost cake and top with walnuts. Store in refrigerator until ready to serve.