Gather all your ingredients. Ensure the butter is softened to room temperature for easier mixing. Peel and dice the apples, setting them aside for later use.

In a medium bowl, combine the all-purpose flour, baking soda, salt, and ground cinnamon. Whisk together until fully mixed.

In a large mixing bowl, cream the softened butter and granulated sugar using an electric mixer on medium speed until light and fluffy, about 3-5 minutes.

Add the eggs one at a time to the creamed mixture, ensuring each is fully incorporated before adding the next. Stir in the vanilla extract.

Gradually add the flour mixture to the wet ingredients, mixing gently until just combined. Fold in the diced apples.

In a separate small bowl, mix the brown sugar, rolled oats, and chopped nuts (if using) until crumbly.

Pour half of the batter into a prepared 9×5 inch loaf pan, sprinkle with half of the streusel topping, add the remaining batter, and top with the rest of the streusel.

Place the loaf pan in a preheated oven and bake for 50-60 minutes or until a toothpick inserted into the center comes out clean.

Let the bread cool in the pan for about 10 minutes, then transfer it to a wire rack to cool completely.

Whisk together the powdered sugar and milk in a small bowl until smooth.