Preheat oven to 350 degrees F (175 degrees C). Grease two 8x4 inch bread pans.
Prepare the topping by combining the 1/2 cup butter, 1/3 cup sugar, vanilla wafers and pecans. Mix together well and press into the bottom of prepared pans.
Cream butter and sugar together. Add eggs one at a time and beat well. Combine milk and vanilla.
Sift flour, baking powder, and salt. Add to batter, alternating with milk; beat well. Pour into prepared loaf pans.
Bake in preheated oven at 350 degrees F (175 degrees C) for 1 hour, or until a toothpick inserted into the cake comes out clean. Remove from oven and cool on wire rack.
