Preheat the oven to 400 degrees. Spray mini muffin cups with cooking spray. You may need to bake in several batches.
Stir the yogurt, milk, oil, eggs, and vanilla until the batter is just blended in a large bowl.
Add the flour, sugar, baking soda, and salt.
Fold in the sprinkles.
Fill prepared muffin cups ¾ full.
Bake in the preheated oven until a toothpick inserted in the center comes out clean, about 9-11 minutes.
Cool in the pans for 10 minutes before removing to cool completely on a wire rack.
Notes
Note on Extracts: I do recommend the extra optional extracts for the best party cake flavor. These give a stronger funfetti-type flavor. Use one teaspoon of vanilla, 1 teaspoon of butter extract, and 1 teaspoon of almond extract. Alternatively, you can use cake batter flavoring to taste.