Preheat oven to 350ºF. Lightly grease two 8- or 9-inch cake pans. Sprinkle a little flour into each pan, then shake the pan around to evenly distribute the flour.
In a large bowl, add flour, sugar, baking soda, and salt. Whisk to combine. Add milk, oil, vinegar, and vanilla; whisk until just combined. Do not overmix; it’s okay if there are some lumps. Add sprinkles; gently stir into the batter. Divide the batter evenly between the two pans.
Bake for 35 minutes, until a toothpick inserted into the center of the cake comes out clean.
Set pans aside for 10 minutes to cool, then remove cake from pan and place on a cooling rack (a trick: place a plate on top of the pan, flip it over so that the cake comes out on the plate, then flip the plate over onto the cooling rack).
When completely cool, decorate with frosting and sprinkles.