Preheat the oven to 350°F.

In a large bowl, whisk together the flour, cocoa, baking soda, and salt. Set aside.

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.

Add the egg and vanilla to the butter mixture and mix for 1-2 more minutes on medium-high speed.

On low speed, add the dry ingredients and mix until just combined.

Line a half cookie sheet with parchment paper and spray with non-stick cooking spray.

Spread the dough into an even layer in the prepared pan.

Bake for just under 10 minutes, until a toothpick comes out clean. Let cool.

Remove the cooled brownie cookie from the pan and cut it in half to make two even pieces.

Place a new piece of parchment paper in the half cookie sheet. Place one half of the brownie back in the sheet.

If using, spread the caramel over the brownie, leaving a 1/2 inch border around the edges.

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.

Freeze for 2 hours or overnight.

Remove from the freezer, trim the edges as needed, and cut into bars. Freeze until ready to serve.