1. Soften peanut butter in the microwave for 15 to 30 seconds. Make sure it's not too runny. Grease a 9x9" cake pan. Preheat oven to 350 degrees Fahrenheit.
2. Mix flour, sugar, cocoa, salt, and baking powder in a bowl. Include the spices in the dry mixture if you choose to use them. In a separate bowl, mix water, oil and vanilla extract.
3. Combine the wet and dry ingredients, making sure not to overwork the batter.
4. Pour 1/2 the batter in the prepared cake pan, followed by the softened peanut butter (spread around, avoiding edges), and then pour the rest of the batter on top. Bake for 30 to 40 minutes.
Source of recipe: I wrote this recipe while playing around in the kitchen.