Preheat your oven to 350°F and line a 12-cup muffin tin with cupcake liners.
In a large bowl, whisk together the sugar, flour, baking powder, baking soda, and salt.
Add the oat milk, vanilla extract, vegetable oil, and egg to the dry ingredients.
Mix the ingredients until just combined, being careful not to overmix to ensure a light and fluffy texture.
Fill each cupcake liner two-thirds full with batter to allow room for the cupcakes to rise.
Bake in the preheated oven for 18 minutes or until a toothpick inserted into the center comes out clean.
After baking, remove the cupcakes from the oven and let them cool completely before frosting.