In mixer bowl of stand mixer, beat together butters and sugars.
Add eggs one at a time, mixing until well combined.
Sift dry ingredients together in a separate bowl. Alternately beat 1/3 of flour mixture and 1/3 of milk into creamed butter mixture until all is used and ingredients are well combined.
Spray 9x5-inch or 8x4-inch loaf pan.
Spread batter into pan, Bake for 1 hour and 20 minutes or until a toothpick inserted in center comes out clean.