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

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

Beat in eggs one at a time, then stir in vanilla extract until well combined.

In a separate bowl, whisk together all-purpose flour, baking powder, baking soda, salt, and ground cinnamon.

Gradually add the flour mixture to the creamed mixture, mixing until just combined.

Fold in chopped nuts and/or mini chocolate chips gently into the dough.

In a small bowl, mix together all-purpose flour, brown sugar, ground cinnamon, and unsalted butter until crumbly for the streusel topping.

Drop rounded dough balls onto the prepared baking sheets, spacing them about 2 inches apart.

Sprinkle the streusel topping generously over each cookie dough ball, pressing down lightly.

Bake for 10-12 minutes until edges are golden and centers appear soft.

Cool on baking sheets for about 5 minutes before transferring to wire racks.