1/4 cupplus 1 tbsp of unsalted buttersoftened to room temperature
2cupspowdered icing sugar
Preheat oven to 350F. Grease and flour a 9" X 13" cake pan and set aside.
In a large bowl add 2 cups sugar, 1 3/4 cups of 1:1 gluten-free flour, 3/4 cup cocoa powder, 1 1/2 tsp baking powder, 1 1/2 tsp baking soda, 1 tsp salt, 1 1/4 tsp cinnamon, 1/2 tsp ground nutmeg, 1/4 tsp cayenne pepper. Mix well to combine.
Add in 2 2ggs, 1 cup milk, 1/2 cup vegetable oil, 2 tsp vanilla and beat on medium-high speed with a handheld mixer for 2 minutes. Add in 1 cup of boiling water and mix well to combine.
Pour the cake batter into the prepared 9" X 13" cake pan. Baked for 30-35 minutes. Cake is done when a toothpick inserted into the centre of the cake comes out clean. Remove from heat and place on a cooling rack to cool in the pan for about 1 hour.
Chocolate Buttercream Frosting
In a medium mixing bowl add 1/4 cup plus 1 tbsp of butter softened to room temperature. Using a hand-mixer beat on high for about 2 minutes or until butter is light and fluffy and starts to look whiter in colour.
Gradually beat in 1 1/2 cups of icing sugar. Add in 4 tbsp of milk and 3/4 tsp vanilla. Continue to beat.
Add in 1/3 cup of cocoa powder and an additional 1/2 cup of icing sugar and continue to beat until well blended.
Using a spatula evenly spread frosting over top of the cake. Decorate with tiny candy-coated chocolate chips, sprinkles or coloured frosting as desired. Serve.
Storage:Will stay fresh on the counter covered tightly for up to 3 days. Freeze for up to 2 months. Defrost overnight in the fridge. Do not freeze with frosting for best flavour and texture.Substitute:Regular all-purpose flour and regular baking powder can be swapped out for their gluten-free alternatives.