Bigger is better sometimes, especially when you’re talking about cookies. Slightly sneaky, this recipe includes whole-wheat flour and chopped walnuts. Top with an easy homemade frosting or just serve alongside a scoop of ice cream.
The dough will be thick like cookie dough, rather than thin like cake batter.
Store the frosting in the fridge, but bring it to room temperature before you want to use it.
Preheat the oven to 350 degrees F. Line a 9-inch cake pan with parchment paper or spray with nonstick cooking spray.
In the bowl of a stand mixer fitted with a paddle attachment, cream with butter and sugar together until creamy. Mix in the egg, yolk, and vanilla on medium speed until thoroughly combined, scraping down the sides of the bowl as you go.
In a medium bowl, add the all-purpose flour, whole-wheat flour, cornstarch, baking soda, and salt. Slowly mix the dry ingredients into the wet ingredients. Mix until thoroughly combined. Add in the chocolate chips and walnuts and mix for a few seconds to combine.
Press the dough into the prepared cake pan, making sure that it’s evenly set. Bake until golden brown on top and slightly more browned along the edges, about 25 minutes.
Set on a wire rack to cool. Once cool enough to touch, remove from the cake pan and cool completely on the rack.
In a small bowl, mix the cream, espresso powder, vanilla, and salt together. In a medium bowl, sift the sugar and cocoa powder together.
In a stand mixer fitted with a paddle attachment, mix the butter until creamy. Add in the cocoa powder and cream mixtures a little at a time, alternating between the two, until thoroughly combined.
Frost the cookie cake as desired, and serve at room temperature.