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

In a medium bowl, whisk together flour, baking soda, ground cinnamon, and salt until well blended.

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

Add the egg and vanilla extract to the creamed mixture, mixing just until combined.

Gradually add the dry mixture to the wet ingredients, stirring until just combined.

Gently fold in the crushed Cinnamon Toast Crunch cereal.

Drop mounds of dough onto the prepared baking sheets, spacing them about 1 inch apart.

Bake for 10-12 minutes, or until the edges are lightly golden.

Cool on the baking sheets for 2-3 minutes before transferring to a wire rack.

For optional icing, mix confectioners' sugar, milk, and cinnamon until smooth, then drizzle over cooled cookies.