Meanwhile, put together your brownie base by mixing together your almond flour, cocoa powder, cornstarch, xanthan gum and salt in a medium bowl. Set this aside.
In another bowl, beat together your eggs, butter, vanilla and sweetener until smooth. Set aside.
In a large microwavable bowl, melt your chocolate-chips and coconut oil in 30s increments, stirring each time until smooth.
Pour your butter and egg mixture into the chocolate-chips and stir until well-incorporated and smooth.
Next stir in your dry ingredients and mix until a thick batter forms. Fold in your additional chocolate-chips if using.
Gently spread your brownie layer on top of the shortbread layer as evenly as possible then bake place everything bake in the pre-heated oven for 25-30min. You want a toothpick to come out relatively clean but be sure not to over-bake your brownies as they will still bake a bit as they cool in the pan. **(These took 35min in my oven but my oven typically bakes on the slower side so just keep that in mind).
Let the brownies cool in the pan on a wire rack for 15-20min before moving them to a fridge to cool for another hour or 2. Once fully cooled, you can cut them into squares and then store them in an airtight container on the counter or freeze them in a container between layers of parchment paper and take them out when you feel like a snack! Enjoy your Keto Shortbread Brownies!