Creating the Spiced Apple Streusel Coffee Cake is a straightforward process. Follow these easy steps for a delicious outcome:

1. Preheat Oven: Preheat your oven to 350°F (175°C). Grease and flour a 9×13-inch baking pan.
2. Mix Dry Ingredients: In a large bowl, whisk together 2 cups of flour, granulated sugar, baking soda, baking powder, salt, cinnamon, and nutmeg.
3. Cream Butter and Sugar: In a separate bowl, cream the softened butter until smooth. Gradually add the sugar and beat until fluffy.
4. Add Eggs and Vanilla: Add the eggs, one at a time, beating well after each addition. Stir in the vanilla extract.
5. Combine Wet and Dry Ingredients: Alternate adding the dry mixture and buttermilk to the creamed mixture. Begin and end with the dry ingredients. Mix until just combined.
6. Fold in Apples: Gently fold in the diced apples until evenly distributed throughout the batter.
7. Prepare Streusel Topping: In a medium bowl, combine ¾ cup flour, brown sugar, and cinnamon. Pour in melted butter and mix until crumbly. Add nuts if desired.
8. Transfer Batter to Pan: Pour the batter into the prepared baking pan, spreading it evenly.
9. Add Streusel Topping: Sprinkle the streusel mixture evenly over the top of the cake batter.
10. Bake: Place in the preheated oven and bake for 40-45 minutes, or until a toothpick inserted in the center comes out clean.
11. Cool: Remove from the oven and allow to cool in the pan for about 15-20 minutes before transferring to a wire rack to cool completely.

By following these simple steps, you’ll create a masterpiece that is sure to delight everyone who tries it!