In a medium bowl, add the wet ingredients (eggs through to vanilla) and whisk together. Be sure to zest the lemon before you squeeze the lemon juice in!
In a separate bowl, add the dry ingredients (excluding the blueberries). Stir to combine.
Add the wet ingredients to the dry ingredients and stir to combine (don't over stir!). Then fold in the frozen blueberries (or fresh blueberries).
Scoop the muffin batter into a muffin tray. I used a mini muffin pan, but you could use a regular sized one if you prefer, see notes below about adjusting cook time. Fill to the top of the muffin pan.
Cook in the oven at 400℉ for 5 minutes. Then reduce the heat to 350℉ and cook for 15-20 minutes, until golden brown on top and cooked through.
Let cool slightly before removing from the pan. Enjoy!
Notes
For mini muffins, cook at 375 degrees F for 15-18 minutes, until golden brown on top and cooked through.