Creating these delightful Coffee Cake Cookies is straightforward. Follow these steps for delicious results:

1. Preheat the Oven: Preheat your oven to 350°F (175°C). Line a baking sheet with parchment paper.
2. Mix Dry Ingredients: In a medium bowl, whisk together the flour, baking powder, baking soda, salt, and cinnamon. Set aside.
3. Cream Butter and Sugar: In a large mixing bowl, cream the softened butter and granulated sugar until light and fluffy.
4. Add Egg and Vanilla: Beat in the egg and vanilla extract until well combined.
5. Incorporate Sour Cream: Mix in the sour cream until smooth.
6. Combine Mixtures: Gradually add the dry ingredients to the wet ingredients, stirring until just combined. Do not overmix.
7. Prepare Topping: In a small bowl, mix brown sugar and chopped nuts (if using) for the streusel topping.
8. Scoop Cookies: Using a cookie scoop or tablespoon, drop rounded balls of dough onto the prepared baking sheet, spacing them about 2 inches apart.
9. Add Topping: Sprinkle the streusel topping generously over each cookie.
10. Bake: Bake in the preheated oven for 10-12 minutes, or until the edges are lightly golden.
11. Cool: Remove from the oven and allow the cookies to cool on the baking sheet for 5 minutes before transferring them to a wire rack to cool completely.
12. Dust with Powdered Sugar: For an extra touch, dust the cooled cookies with powdered sugar before serving.

These steps will guide you through the process, ensuring you create a batch of incredible Coffee Cake Cookies effortlessly.