Preheat your oven to 350°F (175°C) and line baking sheets with parchment paper.

In a large mixing bowl, cream together the softened butter, granulated sugar, and light brown sugar until light and fluffy.

Add eggs one at a time, mixing well after each addition, then stir in vanilla extract.

In a separate bowl, whisk together flour, baking powder, baking soda, salt, and cinnamon. Gradually incorporate this into the wet ingredients.

Alternate adding sour cream with the dry ingredients until fully combined.

Fold in the chopped nuts if using.

Prepare the topping by mixing brown sugar, flour, and cinnamon in a small bowl and cutting in cold butter until crumbly.

Drop about 2 tablespoons of dough onto lined baking sheets, spacing them 2 inches apart.

Sprinkle and gently press the topping over each cookie.

Bake for 12-15 minutes until golden brown.

Let cool on sheets for 5 minutes before transferring to wire racks.