Preheat oven to 400 degrees and line a muffin tin with 12 papers.
In a large bowl, whisk together pancake mix and sugar. Create a well in the center of the mix.
In a separate medium bowl, whisk together eggs, milk, vegetable oil, and vanilla until well combined.
Pour the wet ingredients into the well in the dry ingredients and using a spatula, mix together until just combined, taking care not to over-mix.
Fold in blueberries, chocolate chips, or any other mix-ins you desire.
Fill muffin papers about ¾ of the way with batter and bake for about 18-21 minutes, until muffins are just turning golden and a toothpick inserted into the middle comes out clean.
Let cool in the tin for a couple minutes before moving muffins to rack to cool completely.