Chocolate Christmas Cake

For the Cake:
2 cups all-purpose flour
2 cups granulated sugar
1 tsp baking powder
1 tsp baking soda
1/2 tsp salt
1/2 tsp ground cinnamon (increase to 1 tsp if you prefer a stronger cinnamon flavor)
1 cup unsalted butter
1/4 cup cocoa powder
1 cup water
2 large eggs
1/2 cup buttermilk (or 1/2 cup milk + 1/2 tbsp vinegar, let sit for 5 minutes)
1 tsp vanilla extract

For the Frosting (Optional – Can top with just powdered sugar):
1/2 cup unsalted butter
1/4 cup cocoa powder
1/4 cup milk
3 cups powdered sugar
1/2 tsp ground cinnamon
1 tsp vanilla extract

Instructions
1. Prepare the Cake Batter:
Preheat your oven to 350°F (175°C) and grease a 9×13-inch baking pan.
In a large bowl, whisk together the flour, sugar, baking powder, baking soda, salt, and cinnamon. Set aside.
In a medium saucepan, combine the butter, cocoa powder, and water. Cook over medium heat, stirring occasionally, until the mixture is melted and smooth. Remove from heat.
Pour the chocolate mixture into the dry ingredients and stir to combine.
Add the eggs, buttermilk, and vanilla extract. Mix until smooth and well blended.
2. Bake the Cake:
Pour the batter into the prepared pan and spread evenly.
Bake for 30-35 minutes, or until a toothpick inserted in the center comes out clean.
Allow the cake to cool slightly in the pan while you prepare the frosting.
3. Make the Frosting:
In a medium saucepan, melt the butter over medium heat. Stir in the cocoa powder and milk, and heat until just combined.
Remove from heat and whisk in the powdered sugar, cinnamon, and vanilla extract until smooth.
4. Frost the Cake:
Pour the warm frosting over the slightly cooled cake, spreading it evenly with a spatula.
Allow the cake and frosting to cool completely before slicing and serving.