Preheat the oven to 350°F (180°C). Line two mini muffin pans with paper lines. Lightly oil the papers with cooking spray. Set aside.
In a large mixing bowl, whisk the egg, milk, yogurt, vanilla extract, and oil until smooth.
Stir in sugar, flour, salt, and baking powder. Use a rubber spatula or whisk to bring ingredients together into a smooth muffin batter.
Fold in fresh blueberries, and stir with a spoon to evenly distribute them in the muffin batter.
Use a small cookie scoop to fill each mini muffin cup up to the top.
Bake both mini muffins pan at once for 20-28 minutes. Place one pan in the center rack and one on the rack under it. Bake until muffins are golden brown and a pick inserted in the center of the muffins comes out clean.
Cool down for 5 minutes in the pan, then transfer onto a cooling rack.