Pre-heat your oven to 350 degrees F, place a 8" round cake pan onto a baking sheet and set aside.
Whisk together the flour, cinnamon, baking powder and salt and set aside.
Melt 6 tbsp of the butter in a small sauce pan. Sprinkle in 6 tablespoons of the sugar and cook until the mixture comes to a boil. Sprinkle the melted butter and sugar into the bottom of the cake pan then add the cranberries and chopped walnuts, press the fruit evenly on the bottom of the pan and set aside.
In a stand mixer fitted with a paddle attachment, beat the remaining 8 tbsp of butter on medium speed until smooth, add the remaining 1/2 cup of sugar, blend well scraping down the bowl as needed. Add in the eggs one at a time, then the vanilla, blend until creamy. Turn the mixer down to low and add in 1/2 of the dry ingredients, blend until fully incorporated. Add in the milk and the remaining, blend well.
Spoon the batter over the cranberry mixture and smooth the top with the back of a spoon or spatula. Bake for 40-45 minutes or until a toothpick inserted into the center comes out clean.
Remove the cake from the oven and invert in directly onto a plate, if some of the cranberry mixture sticks just remove it with a spoon and add it onto the cake.
Warm the jelly in a sauce pan until melted and gently brush it over the cake to give it a beautiful shine.