Preheat oven to 350°F.

In a stand mixer, cream butter and sugar until fluffy and pale yellow.

Add eggs one at a time, beating well with each addition.

Add sour cream and mix well.

Sift together dry ingredients and Add gradually mixing on low speed until just incorporated.

Stir in vanilla and set aside.

In a separate bowl combine ingredients for filling.

Grease and flour a very large loaf pan (or two standard loaf pans) and spoon enough batter to just cover the bottom. Use a buttered spatula to smooth out the layer.

Spoon about a third of the filling onto the batter. Repeat the layers until all the batter is used, topping the final layer with the filling mixture.

Bake uncovered for 1hr15mins or until a cake tester comes out clean.

Allow cake to cool in the pan for about 30 minutes. Carefully, remove the cake and wrap in wax paper and tin foil to keep moist.