**Brownie Cookies:**

1. Preheat the oven to 350°F.
2. In a large bowl, whisk together the flour, cocoa, baking soda, and salt. Set aside.
3. In a stand mixer with a paddle attachment (or a bowl with a hand mixer), beat the butter, granulated sugar, and brown sugar on medium-high until light and fluffy, about 2-3 minutes.
4. Add the egg and vanilla to the butter mixture and mix for 1-2 more minutes on medium-high speed.
5. On low speed, add the dry ingredients and mix until just combined.
6. Line a half cookie sheet with parchment paper and spray with non-stick cooking spray.
7. Spread the dough into an even layer in the prepared pan.
8. Bake for just under 10 minutes, until a toothpick comes out clean. Let cool.

**Assembly:**

1. Remove the cooled brownie cookie from the pan and cut it in half to make two even pieces.
2. Place a new piece of parchment paper in the half cookie sheet. Place one half of the brownie back in the sheet.
3. If using, spread the caramel over the brownie, leaving a 1/2 inch border around the edges.
4. Scoop the ice cream over the caramel and spread it into an even layer, leaving a 1/2 inch border around the edges. Place the second brownie layer on top.
5. Freeze for 2 hours or overnight.
6. Remove from the freezer, trim the edges as needed, and cut into bars. Freeze until ready to serve.