Preheat the oven to 180°C (350°F) and line a muffin tin with 12 paper liners.
In a medium-sized bowl, mix the spelt flour, baking powder, baking soda, and a pinch of salt with a spoon. In a separate bowl, whisk together eggs, brown sugar, vegetable oil, buttermilk, and vanilla extract until smooth.
Sieve the flour mixture into the wet ingredients and gently stir until combined. Coat the blueberries in flour, shake the excess off, and fold them into the batter.
Divide the batter evenly among the muffin cups, filling each cup about ¾ full. Optional: If you prefer, sprinkle a little bit of brown sugar on top of each muffin before baking to create a sweet, crunchy topping.
Bake the muffins in the preheated oven for about 20 minutes or until a toothpick inserted into the center of a muffin comes out clean.
Remove the muffins from the oven and let them cool in the muffin tin for a few minutes before transferring them to a wire rack to cool completely.