Preheat oven to 350°F.
Lightly grease an 8″ square or 9″ round pan that’s at least 2″ deep. If you don’t have a 2″-deep pan in either of those sizes, use a 9″ square pan. (I use a 9″ round pan but don’t grease it–just put a nice parchment paper round in the bottom.)
Mix the dry ingredients together in a medium-sized bowl.
Whisk the vanilla, vinegar, oil, and coffee or milk in a separate bowl.
Pour the wet ingredients into the bowl of dry ingredients, stirring until thoroughly combined.
Pour the batter into the prepared pan.
Bake the cake for 30 to 35 minutes, until a toothpick inserted into the center comes out clean, or with a few moist crumbs clinging to it.
Let cool a bit in the pan, then run a knife around the edge to loosen and tump out onto a cooling rack to finish cooling.
Frost with anything from cream cheese icing to whipped cream to a simple dusting of powdered sugar.