Preheat oven to 425°F / 220°C (200° fan-assisted) and line a muffin tray with paper cases of your choice.
In a large bowl, whisk together eggs and sugar until pale and thick (about 20 seconds).
Add the sour cream, oil and vanilla extract and whisk to combine.
In a separate bowl, sift together the flour, baking powder, and salt. Add to the muffin batter and whisk gently until there are no lumps.
Add the blueberries to the muffin batter and fold them in gently with a spatula or wooden spoon.
Scoop batter into the lined muffin pan and fill the cups almost to the top of the liners, leaving about a ¼-inch space at the top. If you like, you can top them with a streusel topping or a sprinkle of brown sugar at this stage.
Bake for 5 minutes at 425°C / 220°C, then turn the oven temperature down to 350°F / 180°C (160° fan-assisted) and bake for a further 13 - 15 minutes. When they are done, they should be golden brown on top, and a skewer inserted should come out clean or with moist crumbs.
Let cool in the muffin pan for 10 minutes before transferring to a wire rack to cool completely.
Notes
Ingredient Notes:Sour Cream - This adds a tangy flavor and gives the muffins a super tender crumb. You can substitute with Greek yogurt if you prefer. Blueberries - You can use fresh or frozen blueberries to make these muffins. If you use frozen, make sure you defrost them completely and drain off any excess liquid before adding to your muffin batter.