Decadent Gluten Free Dairy Free Chocolate Sheet Cake

0 Pre-heat oven to 350F and line a 13x9 cake pan with parchment paper.
1 In a large mixing bowl, add all dry ingredients first and mix gently with a fork to combine.
2 Next, add in all wet ingredients to the dry and using an electric hand mixer, mix on medium low speed until all ingredients are fully incorporated and a thick batter forms.
3 Pour the cake batter into the 13x9 cake pan and smooth out evenly using a silicone spatula.
4 Bake for 30 minutes or until a toothpick comes out clean.
5 While the cake is baking, make the buttercream frosting. Add softened butter + chocolate hazelnut spread to a large mixing bowl. Cream together using an electric hand mixer on medium speed until fluffy, about 1-2 minutes.
6 Next, add powdered monkfruit sugar and cacao powder and continue mixing with an electric hand mixer on low speed. Once powdered sugar and cacao are almost fully incorporated into the chocolate hazelnut spread + butter, add the oat milk and continue mixing on medium low speed another 2-3 minutes. This can be stored at room temperature until cake has cooled. Allow cake to fully cool before frosting.