Preheat oven to 325 degrees Fahrenheit. Grease a 9x5-inch loaf pan. Set aside.
Make the buttermilk substitute. In a small bowl, add vinegar and milk. Whisk the milk mixture briskly to combine. Allow to stand for 5 minutes before using it in the recipe.
In a large mixing bowl, combine the dry ingredients: flour, sugar, baking powder, and baking soda.
In a medium bowl, whisk together the egg and buttermilk substitute until well combined.
Add the wet ingredients into the large bowl containing the flour mixture. Add melted butter and mix just until combined. Do not overmix, or the dough will become tough.
Transfer dough into the greased bread pan.
Bake for 60 to 65 minutes or until a toothpick inserted into the center comes out clean and the crust is golden brown.
Allow to cool on a wire rack for at least 15 minutes before slicing with a serrated knife.
Top with your favorite butter, honey, jam, or jelly!
Notes
You can also use real buttermilk for this recipe, if you have it. Just omit the vinegar and regular milk, and substitute 2 cups of buttermilk.Bonus points for using delicious Irish butter!