Healthy ish Chocolate Snack Cake

Name: Healthy-ish Chocolate Snack Cake
Ingredients: butter and cocoa for pan; 2 cups fortified skim milk (Over the Moon or Skim Plus); 1 teaspoon apple cider vinegar; 1 cup light brown sugar, packed; 3/4 cup granulated sugar; 1 ¾ cups white whole wheat flour; generous 3/4 cup dutch process cocoa powder; ½ teaspoon kosher salt; 1 teaspoon baking powder; 2 teaspoons baking soda; 1 teaspoon instant espresso powder; 1 tablespoon wheat germ; 1/3 cup vegetable oil; 3 eggs; 1 teaspoon vanilla extract; Powdered sugar for dusting