Microwave Chocolate Snack Cake

Ingredients

• FOR CAKE
• 1 1/2 cups all-purpose flour
• 1 cup granulated sugar
• 3 tablespoons unsweetened cocoa powder (I use Ghirardelli brand)
• 1 teaspoon baking soda
• 1/4 teaspoon salt
• 1 cup cold water
• 1/3 cup canola oil
• 1 tablespoon white vinegar or 1 tablespoon apple cider vinegar
• 1 teaspoon vanilla extract
• FOR SAUCE
• 1 cup granulated sugar
• 3 tablespoons cornstarch
• 2 tablespoons unsweetened cocoa powder
• 1 cup boiling water
• 1 tablespoon unsalted butter
• 1 teaspoon vanilla extract
• salt, to taste (optional)