1. Center a rack in oven and heat to 350 degrees.
2. Mix flour, sugar, cocoa powder, and baking soda in an 8" square baking pan until blended.
3. Make one large hole and two smaller holes in dry ingredients using your finger. Pour vanilla into one of the smaller holes, vinegar into the other, and vegetable oil into larger hole. Pour water over top and mix with a fork until mostly smooth, about 3 minutes.
4. Transfer pan to oven and bake until a toothpick inserted into center of cake comes out clean, about 30 minutes. Let cool 15 minutes in pan, then slice into squares and serve warm. (If using frosting, let cool completely before topping and slicing.)
Source: Hannaford fresh Magazine, July - August 2019