Preheat the oven to 350°F (175°C). Lightly grease an 8-inch (20 cm) round cake pan and line the bottom with parchment paper.
In a large mixing bowl, whisk together the all-purpose flour, granulated sugar, baking powder, baking soda, and salt until well combined.
In a separate bowl, combine the unsweetened almond milk, vegetable oil, apple cider vinegar, and pure vanilla extract.
Pour the wet ingredients into the dry ingredients and stir gently with a spatula until just combined. Do not overmix; the batter should be smooth but slightly thick.
Pour the batter into the prepared cake pan and smooth the top with a spatula.
Bake in the preheated oven for 28 to 30 minutes, or until a toothpick inserted into the center comes out clean.
Remove the cake from the oven and allow it to cool in the pan for 10 minutes.
Run a knife around the edges to loosen the cake, then invert it onto a wire rack to cool completely before frosting or serving.