- Preheat the oven to 350°F. Spray 3, 8x4-inch loaf pans with nonstick cooking spray, followed by lining each with parchment paper. Set aside. 
- In a large bowl, cream together the butter and sugar with a hand mixer on medium speed until light and fluffy, about 3-4 minutes. 
- Beat in the eggs one at a time, making sure each one has been incorporated before adding the next one. 
- If adding vanilla, add it to the batter now.  
- Alternating between the flour and milk, add each to the butter mixture, beginning and ending with the flour. Beat until just combined, making sure not to overmix. 
- Pour batter evenly into the prepared loaf pans (about 2½ cups of batter per pan). Bake for 60-65 minutes, or until a toothpick inserted into the center of the cakes comes out mostly clean. 
- Remove from oven and allow to cool in pans for 10 minutes, then remove from the pans. Strip off the parchment paper and let cool completely on wire racks.