Preheat the Oven. Start by preheating your oven to 350°F. Grease and flour a 9x5-inch loaf pan or line it with parchment paper for easy removal.
Prepare the Dry Ingredients. In a medium bowl, whisk together the flour, oats, baking soda, salt, cinnamon, and nutmeg. Set aside.
Cream the Butter and Sugar. In a large mixing bowl, beat the softened butter and brown sugar together until light and fluffy. This should take about 2-3 minutes.
Add Eggs and Vanilla. Beat in the eggs one at a time, followed by the vanilla extract. Continue mixing until well combined.
Mix in the Applesauce. Add the applesauce to the wet ingredients and mix until fully incorporated.
Combine Wet and Dry Ingredients. Gradually add the dry ingredients to the wet mixture, stirring just until combined. Be careful not to overmix, as this can make the bread dense.
Add Optional Mix-Ins. If you’re using nuts or dried fruit, gently fold them into the batter.
Bake. Pour the batter into the prepared loaf pan and smooth the top. Bake in the preheated oven for 55-60 minutes, or until a toothpick inserted into the center comes out clean.
Cool and Serve. Allow the bread to cool in the pan for 10 minutes before transferring it to a wire rack to cool completely. Slater an additional 1/4 of applesauce on top as a frosting if desired. Slice and enjoy!